Air conditioning with recovery wheel, dehumidification wheel, cooling coil, and secondary direct-expansion circuit

ABSTRACT

Systems and methods for controlling temperature and humidity within a space in a building. Outdoor air and return air from the space are passed through particular equipment in a particular order. Equipment includes a secondary direct-expansion refrigeration circuit, a recovery wheel, a primary cooling coil, secondary circuit evaporator and condenser coils, and a dehumidification wheel. Various embodiments include multiple zones, chilled beams, and a dedicated outdoor air supply (DOAS) subsystem delivering dehumidified air to active chilled beams. In various embodiments, supply air passes first through the recovery wheel, then through the primary cooling coil, then through the dehumidification wheel, and then to the space. Further, in some embodiments, exhaust air passes through the dehumidification wheel and then through the recovery wheel. Pump modules may supply chilled beams and control their temperature to avoid condensation. A chiller may supply cooling water to both the primary cooling coil and the pump modules.

RELATED PATENT APPLICATIONS

This United States patent application is a continuation-in-part (CIP)patent application of, and claims priority to, U.S. patent applicationSer. No. 16/712,052, filed Dec. 12, 2019, titled: AIR CONDITIONING WITHRECOVERY WHEEL, DEHUMIDIFICATION WHEEL, AND COOLING COIL, which is: anon-provisional patent application of, and claims priority to, U.S.Provisional patent application Ser. No. 62/779,356, filed Dec. 13, 2018,titled: AIR CONDITIONING IMPROVEMENTS; and (Ser. No. 16/712,05) is alsoa continuation-in-part (CIP) patent application of, and claims priorityto, U.S. patent application Ser. No. 15/616,702, filed Jun. 7, 2017,issued Jun. 23, 2020 as U.S. Pat. No. 10/690,358, titled: AIRCONDITIONING WITH RECOVERY WHEEL, PASSIVE DEHUMIDIFICATION WHEEL,COOLING COIL, AND SECONDARY DIRECT-EXPANSION CIRCUIT, which is anon-provisional patent application of, and claims priority to U.S.Provisional patent application Ser. No. 62/347,517, filed Jun. 8, 2016,also titled: AIR CONDITIONING WITH RECOVERY WHEEL, PASSIVEDEHUMIDIFICATION WHEEL, COOLING COIL, AND SECONDARY DIRECT-EXPANSIONCIRCUIT. In addition, this United States patent application is also acontinuation-in-part (CIP) patent application of, and claims priorityto, U.S. patent application Ser. No. 17/690,805, filed Mar. 9, 2022,titled: MULTI-ZONE CHILLED BEAM SYSTEM AND METHOD WITH PUMP MODULE,which is a non-provisional patent application of, and claims priorityto, U.S. Provisional patent application Ser. No. 63/160,629, filed Mar.12, 2021, also titled: MULTI-ZONE CHILLED BEAM SYSTEM AND METHOD WITHPUMP MODULE. This patent application and these priority patentapplications all have the same inventor and assignee listed above. Inaddition, the contents of these priority patent applications areincorporated herein by reference. If any conflicts exist, however,between this patent application and any documents that are incorporatedby reference, the text of this patent application shall govern herein.

FIELD OF THE INVENTION

Various embodiments of this invention relate to air conditioning units,systems, and methods that control temperature and humidity, for example,within a space within a building. Many embodiments transfer heat,moisture, or both, from outdoor air in a supply airstream to an exhaustairstream. Certain embodiments relate to air conditioning units,systems, and methods that include or use a recovery wheel, adehumidification wheel, a cooling coil, and a secondary direct-expansionrefrigeration circuit. Further, various embodiments include chilledbeams.

BACKGROUND OF THE INVENTION

Heating, ventilating, and air-conditioning (HVAC) systems have been usedto maintain desirable temperatures and humidity levels within buildings,and buildings have been constructed with ventilation systems, includingHVAC systems, to provide comfortable and safe environments for occupantsto live and work. To maintain fresh air within buildings and to reducethe level of indoor air contaminants, in many applications, at least aportion of the air handled by ventilation or HVAC systems has been takenfrom outdoors, while a portion of the indoor air handled by HVAC systemshas been exhausted, for example, to outside the building.

In many situations, outside air introduced to the building to replaceexhaust air must be cooled or heated before being introduced to thebuilding to provide temperatures within desired parameters, and oftenmust be dehumidified or humidified to keep humidity levels withindesired ranges. But adding or removing heat or humidity (moisture)typically involves the expenditure of energy. To reduce the energyrequired to condition the outside air, recovery wheels anddesiccant-based dehumidification wheels, including passivedehumidification wheels, have been used to transfer heat, moisture, orboth, between exhaust air and incoming outside air. Examples of theprior art in these areas are described in U.S. Pat. Nos. 4,769,053 and6,199,388, and U.S. Patent Application publication No. 2004/0000152, allhaving at least one inventor in common with the subject matter of thisdocument, and all of which are incorporated herein by reference in theirentirety. Certain terms, however, may be used differently in thedocuments that are incorporated by reference, and if any conflictsexist, this document shall govern herein. These prior art documents alsodescribe many of the potential needs and benefits of such systems andthe use of recovery wheels.

In addition, cooling coils have been used to cool and dehumidify outdoorair that is introduced to a building, including cooling coils that arecooled with chilled water that has been cooled by one or more chillers.Furthermore, U.S. Pat. No. 6,199,388 describes systems and methods forcontrolling temperature and humidity that include a recovery wheel, apassive dehumidification wheel, and a cooling coil, wherein the systemforms a supply airstream that passes outdoor air first through therecovery wheel, then through the cooling coil, then through thedesiccant-based passive dehumidification wheel, and then to the space,and the system forms an exhaust airstream that passes return air fromthe space first through the desiccant-based passive dehumidificationwheel, and then through the recovery wheel. Examples of prior artsystems are shown in FIGS. 2 and 4.

Further, chilled beams have been used to cool spaces within buildings.Patent application publication No. 20130199772 describes active andpassive chilled beams and is also incorporated herein by reference.Active chilled beams have been used wherein outdoor air is cooled anddehumidified to become supply air, which is delivered to the chilledbeams where the supply air is released into the space through slots ornozzles in a manner that causes induction of room air across a coolingcoil positioned within the chilled beam, thereby substantiallyincreasing cooling capacity delivered to the space. Lower levels ofhumidity in the supply air would be beneficial in some such situationsbecause the chilled beams themselves do not remove humidity from theroom air and the supply air may be the only source of dehumidification.Further still, in chilled beam applications, humidity levels in the roomair can limit the amount of cooling that can be provided through thechilled beams because the chilled beams cannot be cooled below the roomair dew point or else condensation will occur on the chilled beams whichwill drip on the occupants and other contents of the space. Avoidingsuch condensation is necessary or beneficial in many situations.

Still further, chillers that produce chilled water have been used as anefficient way to provide cooling and dehumidification, particularly forlarge buildings. In chilled water systems, however, the minimumtemperature that the air leaving the cooling coil can reach has beenlimited by how cold the chilled water can be produced using traditionalchiller performance limitations. As a result, the amount of humiditythat can be removed from the outdoor air, for example, is limited. Lowerlevels of humidity in the supply air, however, would be beneficial insome situations, for example, where chilled beams are used. In addition,supply air volume (i.e., flow rate) is often desired to be greater thanexhaust air volume to achieve proper building pressurization to preventinfiltration, but in prior art systems, particularly when the imbalancebetween supply air volume and exhaust air volume is sufficiently high,condensation has occurred within the exhaust airstream, for instance, onthe dehumidification wheel or between the dehumidification wheel and therecovery wheel. Avoiding such condensation would be beneficial, if notessential, in many situations. Moreover, in prior art systems, whensupply air was cooled in the cooling coil sufficiently to provide thedesired level of supply air humidity, supply air temperatures were oftencolder than desired. Warmer supply air temperatures would be beneficialin such situations. Needs and opportunities for improvement exist forpartially or fully providing one or more of these needs or potentialbenefits. Room for improvement exists over the prior art in these andvarious other areas that may be apparent to a person of ordinary skillin the art having studied this document.

SUMMARY OF PARTICULAR EMBODIMENTS

This invention provides, among other things, various air conditioningunits, systems, and methods that control temperature and humidity, forinstance, within a space (e.g., in a building). Various units andsystems, for example, include a recovery wheel, a (e.g., passive)dehumidification wheel, a primary cooling coil, a secondary systemevaporator coil, and a secondary system condensing coil. Further, invarious embodiments, a supply airstream passes outdoor air first throughthe recovery wheel, then through the primary cooling coil, then throughthe dehumidification wheel, and then to the space. Still further, inmany embodiments, an exhaust airstream passes return air from the spacethrough the dehumidification wheel, and then through the recovery wheel.Further still, in particular embodiments, the supply airstream passesoutdoor air first through the recovery wheel, then through the primarycooling coil, then through the secondary system evaporator coil, thenthrough the dehumidification wheel, and then to the space. Even further,in certain embodiments, the exhaust airstream passes the return air fromthe space first through the secondary system condensing coil, thenthrough the dehumidification wheel, and then through the recovery wheel.Some embodiments further include chilled beams, for example, in multiplezones within the space.

Various embodiments provide, for example, as an object or benefit, thatthey partially or fully address or satisfy one or more of the needs,potential areas for benefit, or opportunities for improvement describedherein, or known in the art, as examples. For instance, variousembodiments provide for the removal of more moisture from air (e.g.,outdoor air), for instance, in comparison with certain alternatives,while removing much of the enthalpy differential between the outdoor andreturn airstreams using a recovery wheel, a (e.g., passive)dehumidification wheel, and the cooling coil, for example, that iscooled with chilled water that has been cooled by one or more chillers.In some embodiments, for example, systems that primarily use chilledwater for cooling provide as much dehumidification as prior art 100percent direct-expansion systems while providing a higher energyefficiency ratio. Further, various embodiments allow for a greatersupply air volume (i.e., flow rate) than exhaust air volume to achieveproper building pressurization to prevent infiltration, for instance,without forming any or as much condensation within the exhaust airstreambetween the dehumidification wheel and the recovery wheel. Stillfurther, many embodiments provide for supply air temperatures that arenot undesirably cold where such cold temperatures would otherwise havebeen necessary to obtain desired low levels of humidity, or else theinefficient expenditure of energy to reheat supply air would have beenrequired.

Even further, some embodiments provide dryer supply air than certainprior art alternatives (e.g., for compatibility with chilled beams),provide less risk of condensation or better cooling performance of thechilled beams (e.g., due to a lower dew point within the space), or acombination thereof. Certain embodiments provide, for example, asobjects or benefits, for instance, that they improve the performance of(e.g., active) chilled beam systems. Different embodiments simplify thedesign and installation of chilled beam systems, reduce the installedcost of the technology, increase energy efficiency, or a combinationthereof, as examples. In addition, various other embodiments of theinvention are also described herein, and other benefits of certainembodiments may be apparent to a person of ordinary skill in the art.

Specific embodiments include various systems, for instance, forcontrolling temperature and humidity within a space, for example, in abuilding. In a number of embodiments, for example, the system includes arecovery wheel, a (e.g., desiccant-based) dehumidification wheel, aprimary cooling coil, a secondary direct-expansion refrigerationcircuit, and multiple chilled beams. Further, in various embodiments,the secondary direct-expansion refrigeration circuit includes asecondary circuit compressor, a secondary circuit evaporator coil, and asecondary circuit condenser coil. Still further, in a number ofembodiments, the multiple chilled beams are located within the space,the space includes multiple zones, and each zone (e.g., of the multiplezones) includes at least one of the multiple chilled beams (i.e., thatare located within the space). Even further, in various embodiments, thesystem forms a supply airstream, for example, that passes outdoor airfirst through the recovery wheel, then through the primary cooling coil,then through the desiccant-based dehumidification wheel, and then to thespace. Even further still, in a number of embodiments, the system formsan exhaust airstream, for instance, that passes return air from thespace through the desiccant-based dehumidification wheel and thenthrough the recovery wheel.

Further, in some embodiments, the supply airstream passes the outdoorair first through the recovery wheel, then through the primary coolingcoil, then through the secondary circuit evaporator coil, then throughthe desiccant-based dehumidification wheel, and then to the space.Further still, in some embodiments, the exhaust airstream passes thereturn air from the space first through the secondary circuit condensercoil, then through the desiccant-based dehumidification wheel and thenthrough the recovery wheel. Still further, in particular embodiments,the system includes a main chiller, for example, that chills coolingwater that passes through the multiple chilled beams located within thespace. Even further, in certain embodiments, the cooling water from themain chiller also passes through the primary cooling coil. Even furtherstill, in particular embodiments, the multiple chilled beams (e.g.,located within the space) are active chilled beams, the supply airstreamthat passes to the space is delivered to the multiple chilled beams(e.g., located within the space), the supply airstream that passes tothe space induces room air in the space over coils contained within themultiple chilled beams enhancing cooling capacity provided by themultiple chilled beams, or a combination thereof. Moreover, in certainembodiments, the supply airstream that passes to the space fully handleslatent load of the space, the chilled beams handle only sensible load ofthe space, or both such conditions take place.

Still further, in various embodiments, the system includes multiple pumpmodules. Further, in some embodiments, each pump module (e.g., of themultiple pump modules) includes a zone pump, for example, that deliverscooling water to at least one of the multiple chilled beams located inat least one zone of the multiple zones. Further still, in a number ofembodiments, each pump module (e.g., of the multiple pump modules)includes a temperature sensor, a cooling water control valve, a digitalcontroller, or a combination thereof. Even further, in particularembodiments, the temperature sensor measures temperature of the coolingwater, for example, delivered to the at least one of the multiplechilled beams located in the at least one zone of the multiple zones.Even further still, in certain embodiments, the cooling water controlvalve controls passage of cooling water from a cooling water supplyheader into the pump module (e.g., of the multiple pump modules), forexample, to be delivered by the zone pump to the at least one of themultiple chilled beams located in the at least one zone of the multiplezones. Moreover, in particular embodiments, the digital controllercontrols the cooling water control valve, for instance, to controltemperature of cooling water, for example, that is delivered by the zonepump to the at least one of the multiple chilled beams located in the atleast one zone of the multiple zones. Furthermore, in particularembodiments, the digital controller controls the cooling water controlvalve to limit flow of cooling water from the cooling water supplyheader based on a measurement of room air humidity or dew pointtemperature within the zone (e.g., of the multiple zones), for example,at a humidistat located with the zone (e.g., of the multiple zones), forinstance, to avoid formation of condensation on the at least one of themultiple chilled beams located in the at least one zone of the multiplezones, for example, by avoiding having part of the at least one of themultiple chilled beams drop below the dew point temperature within thezone of the multiple zones.

Even further, in a number of embodiments, the recovery wheel is a totalenergy recovery wheel that includes a desiccant coating, the recoverywheel transfers sensible heat, for example, between the outdoor air ofthe supply airstream and the exhaust airstream, the recovery wheeltransfers moisture, for instance, between the outdoor air of the supplyairstream and the exhaust airstream, or a combination thereof. Further,in some embodiments, the desiccant-based dehumidification wheel is apassive dehumidification wheel. Still further, in various embodiments,the system further includes a supply fan, an exhaust fan, a partition,an enclosure, or a combination thereof. Further still, in certainembodiments, the supply fan is located in the supply airstream and movesthe outdoor air first through the recovery wheel, then through theprimary cooling coil, then through the desiccant-based dehumidificationwheel, and then to the space. Even further still, in particularembodiments, the exhaust fan is located in the exhaust airstream andmoves the return air from the space through the desiccant-baseddehumidification wheel and then through the recovery wheel. Moreover, incertain embodiments, the partition is located between the supplyairstream and the exhaust airstream. Furthermore, in variousembodiments, the recovery wheel is located in a first opening in thepartition, the desiccant-based dehumidification wheel is located in asecond opening in the partition, or both. In addition, in someembodiments, at least adjacent to the partition, the supply airstreamand the exhaust airstream travel in (e.g., substantially) oppositedirections. Further, in a number of embodiments, the enclosure containsthe recovery wheel, the desiccant-based dehumidification wheel, theprimary cooling coil, the secondary circuit evaporator coil, thesecondary circuit condenser coil, at least part of the supply airstream,at least part of the exhaust airstream, the partition, or a combinationthereof.

Further still, in various embodiments, the system includes a systemcontroller. In a number of embodiments, for example, the systemcontroller is configured to operate the secondary circuit compressor,for example, whenever the system is operating in a cooling mode,whenever the system is operating in a dehumidification mode, or both.Further, in some embodiments, the system controller is configured tomodulate cooling at the primary cooling coil, for example, to controltemperature of the space when operating in the cooling mode, to controlabsolute humidity level or dew point of the space when operating in thedehumidification mode, or both. Even further, in particular embodiments,the system controller is configured to modulate cooling at the primarycooling coil, for instance, to control temperature of the supplyairstream delivered to the space when operating in the cooling mode, tocontrol absolute humidity level or dew point of the supply airstreamdelivered to the space when operating in the dehumidification mode, orboth. Still further, in some embodiments, the system controller isconfigured to: modulate the secondary circuit compressor, for example,to adjust reheat capacity at the secondary condenser coil when operatingin a cooling mode, modulate rotational speed of the dehumidificationwheel, for instance, based on a measured temperature of the supplyairstream delivered to the space, for example, to control temperature ofthe supply airstream delivered to the space, or both. Even furtherstill, in certain embodiments, the system controller is configured tooperate the system in an economizer mode, for example, in which coolingat the primary cooling coil is turned off and the secondary circuitcompressor is operated, for instance, to dehumidify the supply airstreamwith the secondary circuit evaporator coil and the desiccant-baseddehumidification wheel.

Even further still, in some embodiments, the system controller isconfigured to operate the system in a part-load or recirculation mode,for example, in which cooling at the primary cooling coil is modulateddown or off and cooling at the secondary cooling coil is modulated, forinstance, to dehumidify the supply airstream using the desiccant-baseddehumidification wheel. Further, in particular embodiments, the systemcontroller is configured to lower speed, capacity, or both, of thesecondary direct expansion circuit compressor, lower rotational speed ofthe dehumidification wheel, or a combination thereof, for example, whendew point or humidity level in the space drops below a setpoint dewpoint or humidity level threshold. Still further, in particularembodiments, the system controller is configured to increase speed,capacity, or both, of the secondary direct expansion circuit compressor,increase rotational speed of the dehumidification wheel, or acombination thereof, for example, when dew point or humidity level inthe space exceeds the setpoint dew point or humidity level threshold.Further still, in certain embodiments, the system controller isconfigured to lower speed or capacity (or both) of the secondary directexpansion circuit compressor, for instance, when dew point or humiditylevel in the space drops below a setpoint dew point or humidity levelthreshold, for example, when supply air temperature or space temperatureis below a setpoint temperature threshold. Even further, in someembodiments, the system controller is configured to increase the speedor capacity (or both) of the secondary direct expansion circuitcompressor, for example, when the dew point or humidity level in thespace exceeds the setpoint dew point or humidity level threshold, forinstance, when the supply air temperature or the space temperature isabove the setpoint temperature threshold. Moreover, in particularembodiments, the system controller is configured to lower rotationalspeed of the dehumidification wheel, maintain speed or capacity of thesecondary direct expansion circuit compressor, or both, for example,when dew point or humidity level in the space drops below a setpoint dewpoint or humidity level threshold, supply air temperature or spacetemperature is above the temperature setpoint threshold, or acombination thereof. Furthermore, in certain embodiments, the systemcontroller is configured to increase the rotational speed of thedehumidification wheel, maintain the speed or capacity of the secondarydirect expansion circuit compressor, or both, for example, when the dewpoint or humidity level in the space or supply air exceeds the setpointdew point or humidity level threshold, the supply air temperature orspace temperature is below the temperature setpoint threshold, or acombination thereof.

In particular embodiments, the system controls temperature and humiditywithin the space (e.g., in the building), for example, including (e.g.,simultaneously) operating the secondary circuit compressor of thesecondary direct-expansion refrigeration circuit, passing the outdoorair first through the recovery wheel, then through the primary coolingcoil, then through the secondary circuit evaporator coil, then throughthe desiccant-based dehumidification wheel, and then to the space,passing the return air from the space first through the secondarycircuit condenser coil, then through the desiccant-baseddehumidification wheel, and then through the recovery wheel, or acombination thereof. Further, in various embodiments, the system (e.g.,simultaneously) transfers a first quantity of heat from the outdoor airentering the supply airstream to the exhaust airstream, cools the supplyairstream downstream of where the system transfers the first quantity ofheat, for example, including condensing a second quantity of moisturefrom the supply airstream, transfers a third quantity of heat from thesupply airstream to the return air entering the exhaust airstream, or acombination thereof. Still further, in particular embodiments, the thirdquantity of heat is transferred from the supply airstream downstream ofwhere the system condenses the second quantity of moisture from thesupply airstream, the transferring of the third quantity of heat fromthe supply airstream includes condensing a fourth quantity of moisturefrom the supply airstream, the transferring of the third quantity ofheat from the supply airstream to the return air entering the exhaustairstream is performed using the secondary direct-expansionrefrigeration circuit, or a combination thereof. Even further, in someembodiments, the system transfers a fifth quantity of moisture from thesupply airstream to the exhaust airstream. For example, in particularembodiments, the fifth quantity of moisture is transferred from thesupply airstream to the exhaust airstream in the supply airstreamdownstream of where the third quantity of heat is transferred from thesupply airstream to the return air entering the exhaust airstream.Further still, in some embodiments, the fifth quantity of moisture istransferred from the supply airstream to the exhaust airstream in theexhaust airstream downstream of where the third quantity of heat istransferred from the supply airstream to return air entering the exhaustairstream.

Moreover, in some embodiments, for example, in conjunction withtransferring the fifth quantity of moisture from the supply airstream tothe exhaust airstream, the system transfers a sixth quantity of (e.g.,sensible) heat from the exhaust airstream to the supply airstream.Furthermore, in particular embodiments, the transferring of the sixthquantity of (e.g., sensible) heat from the exhaust airstream to thesupply airstream takes place in the supply airstream downstream of wherethe third quantity of heat is transferred from the supply airstream tothe return air entering the exhaust airstream, the sixth quantity of(e.g., sensible) heat is transferred from the exhaust airstream to thesupply airstream in the exhaust airstream downstream of where the thirdquantity of heat is transferred from the supply airstream to the returnair entering the exhaust airstream, or both. Further, in someembodiments, the system delivers the supply airstream to the spacedownstream of where the sixth quantity of (e.g., sensible) heat istransferred from the exhaust airstream to the supply airstream. Stillfurther, in various embodiments, the delivering of the supply airstreamto the space takes place in the supply airstream downstream of where thefifth quantity of moisture is transferred from the supply airstream tothe exhaust airstream, the first quantity of heat is transferred fromthe outdoor air entering the supply airstream to the exhaust airstreamin the exhaust airstream downstream of where the fifth quantity ofmoisture is transferred from the supply airstream to the exhaustairstream, or both.

In certain embodiments, the first quantity of heat includes bothsensible and latent heat. Further, in some embodiments, the transferringof the first quantity of heat from the outdoor air entering the supplyairstream to the exhaust airstream includes transferring a seventhquantity of moisture from the outdoor air entering the supply airstreamto the exhaust airstream. Further still, in particular embodiments, thetransferring of the seventh quantity of moisture from the outdoor airentering the supply airstream to the exhaust airstream takes place inthe exhaust airstream downstream of where the fifth quantity of moistureis transferred from the supply airstream to the exhaust airstream. Evenfurther, in certain embodiments, cooling of the supply airstreamdownstream of the transferring of the first quantity of heat includesremoving an eighth quantity of heat from the supply airstream, rejectingthe eighth quantity of heat to the exhaust airstream, for example,downstream of where the first quantity of heat is transferred to theexhaust airstream, or both. In addition, various other embodiments(e.g., of the invention) are also described herein, and other benefitsof certain embodiments may be apparent to a person of ordinary skill inthe art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an example of an air conditioning unit, HVACunit, or system for controlling temperature and humidity within a spacein a building that illustrates a number of embodiments of the invention;

FIG. 2 is a block diagram of an example of a prior art air conditioningunit, HVAC unit, or system for controlling temperature and humiditywithin a space in a building, illustrating a prior art problem ofcondensation within the unit or system, for example, at thedehumidification wheel, when supply air with a low dew point isproduced;

FIG. 3 is a block diagram of an example of an air conditioning unit,HVAC unit, or system for controlling temperature and humidity within aspace in a building, that illustrates certain embodiments of theinvention, and that illustrates how the prior art problem ofcondensation within the unit or system (e.g., illustrated in FIG. 2) ,for example, on the dehumidification wheel, can be overcome whileproducing supply air with an even lower dew point;

FIG. 4 is a block diagram of the example of FIG. 2 of the prior art airconditioning unit, HVAC unit, or system for controlling temperature andhumidity within a space in a building, illustrating a prior art problemof condensation within the unit when there is substantial flowimbalance;

FIG. 5 is a psychometric chart illustrating limitations of the prior artair conditioning unit, HVAC unit, or system of FIGS. 2 and 4;

FIG. 6 is a block diagram of the example of FIG. 3 of the airconditioning unit, HVAC unit, or system for controlling temperature andhumidity within a space in a building, that illustrates certainembodiments of the invention, and that illustrates how the prior artproblem of condensation within the unit or system, when there issubstantial flow imbalance (e.g., illustrated in FIG. 4) can beovercome;

FIG. 7 is a block diagram of the example of FIGS. 3 and 6 of the airconditioning unit, HVAC unit, or system for controlling temperature andhumidity within a space in a building, that further illustrates how theprior art problem of condensation within the unit when there issubstantial flow imbalance (e.g., illustrated in FIG. 4) can be overcomeby certain embodiments of the invention while delivering an even lowerdew point than shown in FIG. 6;

FIG. 8 is a psychometric chart illustrating performance of the airconditioning unit, HVAC unit, or system of FIGS. 3, 6, and 7;

FIG. 9 is a block diagram of the example of FIGS. 3, 6, and 7 of the airconditioning unit, HVAC unit, or system for controlling temperature andhumidity within a space in a building, that illustrates how the unit orsystem can perform when there is no primary cooling (e.g., when theprimary cooling coil chilled water or primary direct expansion circuitis turned off);

FIG. 10 illustrates an example of an equipment layout for certainembodiments of the invention;

FIG. 11 is a plan view of an example of an air conditioning unit, HVACunit, or system for controlling temperature and humidity within a spacein a building that illustrates several embodiments of the inventionhaving a primary direct expansion refrigeration circuit with thecondenser coil located in the exhaust airstream;

FIG. 12 is a flow chart illustrating an example of method forcontrolling temperature and humidity within a space in a building,

FIG. 13 is a flow chart illustrating another example of method forcontrolling temperature and humidity within a space in a building;

FIG. 14 is a plan view and block diagram illustrating an example of anair conditioning unit, HVAC unit, or system for controlling temperatureand humidity within a space in a building that illustrates a number ofembodiments that include an evaporative cooler, supplemental outdoorair, or both;

FIG. 15 is a plan view and block diagram illustrating part of a unitthat illustrates another embodiment that has an evaporative cooler,supplemental outdoor air, or both;

FIG. 16 is a block diagram illustrating an example of a system thatincludes a Variable Refrigerant Flow (VRF) subsystem and a dedicatedoutdoor air supply (DOAS) that each feed multiple zones;

FIG. 17 is a block diagram illustrating an example of a direct expansionrefrigeration circuit that may be a geothermal direct expansionrefrigeration circuit and may condition one of multiple zones; and

FIG. 18 is a block diagram illustrating an example of a chiller circuitthat includes a chiller, a cooling coil, and a cooling tower.

The drawings and written materials provided herewith illustrate, amongother things, examples of certain aspects of particular embodiments.Other embodiments may differ. Various embodiments may include aspectsshown in the drawings, described in the specification (including theclaims), known in the art, or a combination thereof, as examples.

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENTS

This patent application describes, among other things, examples ofcertain embodiments, and certain aspects thereof. Other embodiments maydiffer from the examples described in detail herein. Various embodimentsinclude systems for controlling temperature and humidity, for example,within a space in a building. Such systems can be or include, forexample, air conditioning units or HVAC units. FIGS. 1, 3, 5, 6, 7, 9,10 and 11 illustrate examples of systems for controlling temperature andhumidity, for example, within a space in a building, air conditioningunits, or HVAC units. In many embodiments, such a unit or system (e.g.,100, 300, 1000, or 1100) includes a recovery heat exchanger, forexample, a recovery wheel (e.g., 110, 310, or 1010), a (e.g., passive)dehumidification wheel (e.g., 130, 330, or 1030), a primary cooling coil(e.g., 150, 350, 1050, or 1150), a secondary cooling coil (e.g., 160,360, or 1060), and a heating coil (e.g., 140, 340, or 1040), forexample, a condensing coil.

Further, in various embodiments, the unit or system forms a supplyairstream (e.g., 335 shown in FIG. 3 or 1135 shown in FIG. 11) thatpasses outdoor air (e.g., 305) first through the recovery heat exchangeror recovery wheel (e.g., 110 or 310), then through the primary coolingcoil (e.g., 150, 350, or 1150), then through the secondary cooling coil(e.g., 160 or 360), then through the dehumidification wheel (e.g., 130or 330), and then to the space. In many embodiments, the supplyairstream (e.g., 335 or 1135) starts as outdoor air (e.g., 305), andthen is cooled, dehumidified, and partially reheated, for example, bythe recovery heat exchanger or recovery wheel (e.g., 110 or 310), theprimary cooling coil (e.g.,150, 350, or 1150), the secondary coolingcoil (e.g., 160 or 360), and the dehumidification wheel (e.g., 130 or330) to become supply air (e.g., 337) that is delivered to the space.Still further, in a number of embodiments, the system (e.g., 300 or1100) forms an exhaust airstream (e.g., 315 or 1115) that passes exhaustair or return air (e.g., 345 or 1145), for example, from the space,first through the heating coil (e.g., 140 or 340, for example, thesecondary condensing coil), then through the dehumidification wheel(e.g., 130 or 330), and then through the recovery wheel (e.g., 110 or310), for example. In this context, the words “first” and “then” areused to describe the order in which a particular portion of air, of manysuch portions, passes through various pieces of equipment in theparticular embodiment described. It should be understood, however, thatdifferent portions of the air pass through these different pieces ofequipment simultaneously. Further, where an airstream is describedherein as passing through various pieces of equipment in a particularorder, it should be understood that different parts of the airstream maybe passing through the various pieces of equipment at the same time, butthat the order in which a particular portion of air passes through thevarious pieces of equipment is what is being described.

In different embodiments, the heating coil (e.g., 140 or 340) is orincludes a waste-heat heating coil (e.g., a condensing coil for an airconditioning unit or cycle, for instance, 125 or 325). Further, manyembodiments include a secondary direct-expansion refrigeration circuit(e.g., 125 or 325), for instance, that includes (e.g., among otherthings) a secondary direct-expansion refrigeration circuit compressor(e.g., 120, 320, or 1020), a secondary direct-expansion refrigerationcircuit evaporator coil (e.g., 160 or 360), a secondary direct-expansionrefrigeration circuit condenser coil (e.g., 140 or 340), or acombination thereof. In some embodiments, for example, the trim coil orsecondary cooling coil is or includes the secondary direct-expansionrefrigeration circuit evaporator coil (e.g., 160 or 360). Still further,in some embodiments, the heating coil is or includes the secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or340), for example. Heat from the condenser of an air conditioningcircuit that is used primarily for cooling is an example of waste heat,but in some other embodiments, other sources of waste heat can be used.Further, in some embodiments, a direct-expansion refrigeration circuitcan reject heat to a location other than to the return air (e.g., 345 or1145) or exhaust airstream (e.g., 315 or 1115), such as to outdoor airoutside the building or to a geothermal heat sink, as examples. But inmany such embodiments, a remote condensing section is required and itmay be necessary to route refrigerant lines a considerable distance tothe condenser. Embodiments that include a secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) with a secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or 340)that rejects heat to the return air (e.g., 345 or 1145) or exhaustairstream (e.g., 315 or 1115) can allow for much shorter refrigerantlines. Further still, in a number of embodiments, the dehumidificationwheel (e.g., 130 or 330) is a desiccant-based or passivedehumidification wheel, or both. In some embodiments, bypass dampers areprovided, for example, for the dehumidification wheel, to bypass thewheel when the wheel is not needed.

In various embodiments, the system (e.g., 100, 300, or 1100) forms asupply airstream (e.g., 335 or 1135) that passes outdoor air (e.g.,305), for example, first through the recovery heat exchanger or recoverywheel (e.g., 110 or 310), then through the primary cooling coil(e.g.,150, 350, or 1150), then through the secondary direct-expansionrefrigeration circuit evaporator coil (e.g., 160 or 360), then throughthe dehumidification wheel (e.g., 130 or 330), and then to the space.Even further, in many embodiments, the system (e.g., 100, 300, or 1100)forms an exhaust airstream (e.g., 315 or 1115) that passes return air(e.g., 345 or 1145) from the space first through the secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or340), then through the dehumidification wheel (e.g., 130 or 330), andthen through the recovery heat exchanger or recovery wheel (e.g., 110 or310). In a number of embodiments, passing the return air (e.g., 345 or1145) from the space first through heating coil (e.g., 140 or 340) orthe secondary direct-expansion refrigeration circuit condenser coil(e.g., 140 or 340), and then through the (e.g., desiccant-based)dehumidification wheel (e.g., 130 or 330) preheats the exhaust airstream(e.g., 315 or 1115) or return air (e.g., 345 or 1145) entering thedehumidification wheel (e.g., 130 or 330) and reduces the relativehumidity of the exhaust airstream (e.g., 315 or 1115) that passesthrough the dehumidification wheel (e.g., 130 or 330), which thenremoves moisture from the dehumidification wheel (e.g., 130 or 330) moreeffectively. In some embodiments, this can result in an improvement indehumidification capacity (e.g., of 10 to 25 percent) with, in someembodiments, the same or similar temperature of the supply airstream(e.g., 335 or 1135) leaving the secondary cooling coil (e.g., 160 or360) or secondary direct-expansion refrigeration circuit (e.g., 125 or325) evaporator coil (e.g., 160 or 360).

In many embodiments, the recovery heat exchanger is a recovery wheel(e.g., 110 or 310). In other embodiments, however, the recovery heatexchanger is a plate-type air to air heat exchanger, as an example, or adifferent type of heat exchanger. Where a recovery wheel is describedherein, other embodiments utilize instead a recovery heat exchangergenerally, which can be a recovery wheel (e.g., 110 or 310), aplate-type air to air heat exchanger, or a different type of heatexchanger. Further, where a recovery wheel is described herein, aplate-type air to air heat exchanger is specifically contemplated inother particular embodiments. In a number of embodiments, when operatingin a cooling mode, the recovery wheel (e.g., 110 or 310) transferssensible heat from the outdoor air (e.g., 305) of the supply airstream(e.g., 335 or 1135) to the exhaust airstream (e.g., 315 or 1115).Further, in some embodiments, the recovery wheel (e.g., 110 or 310) is atotal energy recovery wheel, for example, that includes a desiccantcoating. In various embodiments, under appropriate conditions (e.g.,when operating in a cooling mode with sufficient outdoor air humidity,or when operating in a dehumidification mode), the recovery wheel (e.g.,110 or 310) transfers moisture from the outdoor air (e.g., 305) of thesupply airstream (e.g., 335 or 1135) to the exhaust airstream (e.g., 315or 1115).

In a number of embodiments, the system (e.g., 100, 300, or 1100)includes a supply fan (e.g., 113, 313, or 1113), for example, located inthe supply airstream (e.g., 335 or 1135), that moves the outdoor air(e.g., 305) first through the recovery wheel (e.g., 110 or 310), thenthrough the primary cooling coil (e.g., 150, 350, or 1150), then throughthe secondary cooling coil or secondary direct-expansion refrigerationcircuit evaporator coil (e.g., 160 or 360), then through the (e.g.,desiccant-based, passive, or both) dehumidification wheel (e.g., 130 or330), and then to the space. In particular embodiments, for example, thesupply fan is located in the supply airstream, for example, between thedehumidification wheel and the space. In other embodiments, as anotherexample (e.g., as shown), the supply fan (e.g., 113, 313, or 1113) is inthe supply airstream (e.g., 335 or 1135) between the recovery wheel(e.g., 110 or 310) and the primary cooling coil (e.g., 150, 350, or1150). Further, in various embodiments, the system (e.g., 300) includesan exhaust fan (e.g., 312), for example, located in the exhaustairstream (e.g., 315), that moves the return air (e.g., 345) from thespace first through the heating coil or (e.g., secondarydirect-expansion refrigeration circuit condenser coil (e.g., 340), thenthrough the dehumidification wheel (e.g., 330), and then through therecovery wheel (e.g., 310). In some embodiments, for example, theexhaust fan (e.g., 312) is located in the exhaust airstream (e.g., 315)downstream of the recovery wheel (e.g., 310). In this context, as usedherein, “downstream” is relative to the direction of flow of the exhaustairstream (e.g., 315). FIG. 1 also shows exhaust fan 112, which issimilarly located.

In many embodiments, the system (e.g., 100 or 300) further includes aprimary chiller (not shown), for example, that chills cooling water thatpasses through the primary cooling coil (e.g.,150 or 350). In someembodiments, the primary chiller includes multiple chillers. Moreover,in various embodiments, the primary chiller is separate from thesecondary direct-expansion refrigeration circuit system (e.g., 125 or325) or compressor (e.g., 120 or 320), or from both.

Further, various embodiments further include a partition (e.g., 111 or311 shown in FIGS. 1, 3, 6, and 11), for instance, (e.g., with referenceto FIGS. 3 and 11) between the supply airstream (e.g., 335 or 1135) andthe exhaust airstream (e.g., 315 or 1115). In a number of embodiments,for example, the recovery wheel (e.g., 310) is located in a firstopening (e.g., 601 shown in FIG. 6) in the partition (e.g., 311), the(e.g., passive) dehumidification wheel (e.g., 330) is located in asecond opening (e.g., 602) in the partition (e.g., 311), or both (e.g.,as shown). In various embodiments, the partition (e.g., 111 or 311) is awall, for example, within the system or air conditioning or HVAC unit(e.g., 100, 300, or 1100), that separates the two airstreams. In someembodiments, for example, the partition (e.g., 111 or 311) is sheetmetal. In particular embodiments, for instance, the partition (e.g., 111or 311) is insulated or includes a layer of insulation.

In various embodiments, at least adjacent to the partition (e.g., 111 or311), the supply airstream (e.g., 335 or 1135) and the exhaust airstream(e.g., 315 or 1115) travel in substantially parallel directions (e.g.,as shown). Further, in many embodiments, at least adjacent to thepartition (e.g., 111 or 311), the supply airstream (e.g., 335 or 1135)and the exhaust airstream (e.g., 315 or 1115) travel in substantiallyopposite directions (e.g., as shown). As used herein, when referring toan angle, “substantially” means to within 10 degrees. In someembodiments, however, at least adjacent to the partition (e.g., 111 or311), the supply airstream (e.g., 335 or 1135) and the exhaust airstream(e.g., 315 or 1115) travel in parallel directions, in oppositedirections, or both, to within 1, 2, 3, 5, 7, 15, 20, or 25 degrees, asother examples. Moreover, as used herein “parallel directions” includes“opposite directions” (e.g., parallel but opposite).

Still further, in various embodiments, the system or unit furtherincludes an enclosure (e.g., an air conditioning unit enclosure), forexample, that contains the recovery wheel (e.g., 110 or 310), thedehumidification wheel (e.g., 130 or 330), the primary cooling coil(e.g., 150, 350, or 1150), the secondary cooling coil (e.g., 160 or360), the secondary direct-expansion refrigeration circuit (e.g., 125 or325), the secondary circuit evaporator coil (e.g., 160 or 360), theheating coil or secondary direct-expansion refrigeration circuitcondenser coil (e.g., 140, 340, or 1140), at least part of the supplyairstream (e.g., 335 or 1135), at least part of the exhaust airstream(e.g., 315 or 1115), or a combination (e.g., all) thereof (e.g., asshown). FIGS. 1 and 11, for example, show enclosure 101. In someembodiments, for further example, the enclosure (e.g., 101) contains thepartition (e.g., 111). In many embodiments, for example, the enclosure(e.g., 101) is or includes sheet metal and has, for example, multipledoors or removeable access panels for access therein (e.g., as shown).In particular embodiments, for instance, the enclosure (e.g., 101) isinsulated (e.g., in whole or in part) or includes a layer of insulation.In certain embodiments, part or all of the enclosure is part of thebuilding (e.g., walls, floor, etc.). Further still, in variousembodiments, the partition (e.g., 111) extends to or connects to theenclosure (e.g., 101), for instance, as shown. Even further, in someembodiments, the enclosure (e.g., 101) further contains the supply fan(e.g., 113 shown in FIG. 1), the exhaust fan (e.g., 112), or both (e.g.,as shown). Even further still, in some embodiments, the enclosure (e.g.,101) further contains the secondary direct-expansion refrigerationcircuit (e.g., 125), for example, including the secondarydirect-expansion refrigeration circuit compressor (e.g., 120). In anumber of embodiments, the secondary direct-expansion refrigerationcircuit compressor (e.g., 120 or 320) is located in the exhaustairstream (e.g., 315 or 1115).

In addition, in some embodiments, the system or unit includes a primaryheating coil, for instance, located in the supply airstream, forexample, for heating the supply airstream when operating the system in aheating mode. In some embodiments, the primary heating coil is inaddition to the primary cooling coil (e.g., 150, 350, or 1150). In anumber of embodiments, for example, the enclosure further contains theprimary heating coil. Moreover, in many embodiments, the system (e.g.,for controlling temperature and humidity within a space in a building)further includes ductwork, for example, supply ductwork that deliversthe supply airstream (e.g., 335 or 1135), for example, from thedehumidification wheel (e.g., 130 or 330), or the supply air (e.g., 337)to the space. In various embodiments, the ductwork is outside of theenclosure (e.g., 101), connects to the enclosure, or both, as examples.Further, in a number of embodiments, the space includes multiple zones.Still further, in some embodiments the system includes supply ductworkthat delivers the supply airstream (e.g., 335 or 1135) to (e.g., eachof) the multiple zones. Even further, in many embodiments, the ductworkincludes return ductwork, for example, that delivers the return air(e.g., 345 or 1145) from the space or zones to become the exhaustairstream (e.g., 315 or 1115).

In various embodiments, the system (e.g., for controlling temperatureand humidity within a space in a building) further includes multiplechilled beams, for example, located within the space, for instance,within the zones. Further, in a number of embodiments, the systemincludes a main chiller that chills cooling water that passes throughthe multiple chilled beams. Still further, in some embodiments, thecooling water from the main chiller also passes through the primarycooling coil (e.g., 150 or 350), for example, in parallel, or in series(e.g., first through the primary cooling coil (e.g., 150 or 350). Insome embodiments, the primary chiller and the main chiller, as describedherein, are the same chiller (or chillers) while in other embodiments,the primary chiller and the main chiller are separate chillers (or setsof chillers). Even further, in various embodiments, the multiple chilledbeams (e.g., located within the space or zones) are active chilledbeams. Further still, in a number of embodiments, the supply airstream(e.g., 335 or 1135) that passes to the space is delivered to themultiple chilled beams located within the space. Even further still, insome embodiments, the supply airstream (e.g., 335 or 1135) that passesto the space induces room air in the space over or across the coolingcoils within the multiple chilled beams, for example, enhancing coolingcapacity delivered by the multiple chilled beams. As used herein, inthis context, “over” includes along and in contact with. In someembodiments, the room air moves through passageways or between fins ofthe chilled beams, as examples.

In some embodiments in which the space includes multiple zones, each ofthe multiple zones includes at least one of the multiple chilled beams(e.g., that are located within the space). Further, in certainembodiments, the system (e.g., for controlling temperature and humiditywithin a space in a building) further includes a chilled water zonepump, for example, for each of the multiple zones. In a number ofembodiments, for instance, the chilled water zone pump circulateschilled water through at least one of the multiple chilled beams thatare located within that zone (i.e., the zone that the particular chilledwater zone pump serves). Still further, in certain embodiments, thesystem (e.g., for controlling temperature and humidity within a space ina building) further includes a chilled water temperature sensor, forexample, for each of the multiple zones, that measures temperature ofthe chilled water that passes through the (e.g., at least one of themultiple) chilled beams that are located within that zone (e.g., thezone that the particular chilled water temperature sensor serves). Evenfurther, a number of embodiments further include a chilled water controlvalve, for instance, for each of the multiple zones, that passes chilledwater from a chilled water supply header into the (e.g., at least one ofthe multiple) chilled beams, for example, that are located within thatzone (e.g., the zone that the particular chilled water control valveserves).

Various embodiments include a digital controller, for example, for eachof the multiple zones, for instance, that controls flow of chilled waterfrom the chilled water supply header into the (e.g., at least one of themultiple) chilled beams, for example, that are located within that zone.In some embodiments, the digital controller (e.g., for each of themultiple zones) limits flow of chilled water from the chilled watersupply header into the (e.g., at least one of the multiple) chilledbeams, for instance, that are located within that zone (e.g., the zonethat the particular digital controller serves). In particularembodiments, for example, the digital controller (e.g., for each of themultiple zones) limits flow of chilled water from the chilled watersupply header into the (e.g., at least one of the multiple) chilledbeams, for instance, to avoid formation of condensation on the (e.g., atleast one of the multiple) chilled beams, for example, that are locatedwithin that zone. For example, in a number of embodiments, thecontroller limits flow of chilled water from the chilled water supplyheader into the (e.g., at least one of the multiple) chilled beams tocontrol temperature of the chilled beam(s), for example, to avoid havingpart of the beam(s) drop below the dew point temperature within thespace. In various embodiments, for example, the digital controller(e.g., for each of the multiple zones) controls flow of chilled water,for example, from the chilled water supply header, into the (e.g., atleast one of the multiple) chilled beams (e.g., that are located withinthat zone) based on or in response to a measurement of the room airhumidity or dew point within the zone, for instance, at a humidistatlocated with that zone. Further, in various embodiments, the digitalcontroller (e.g., for each of the multiple zones) controls flow ofchilled water, for example, from the chilled water supply header, intothe (e.g., at least one of the multiple) chilled beams (e.g., that arelocated within that zone) to control room air temperature within thatzone, for example, in response to a measurement of the room airtemperature within the zone for instance, at a thermostat located withthat zone (e.g., in addition to controlling temperature to preventcondensation).

Further, certain embodiments (e.g., of a system for controllingtemperature and humidity within a space in a building) include ageothermal heat sink. In some embodiments, for example, heat from theprimary cooling coil (e.g.,150, 350, or 1150) is rejected to thegeothermal heat sink. Still further, some embodiments (e.g., of a systemfor controlling temperature and humidity within a space in a building)include a direct-expansion refrigeration circuit, for instance, thatuses the geothermal heat sink as a geothermal condenser in a coolingmode. Even further, in various embodiments, the direct-expansionrefrigeration circuit uses the geothermal heat sink as an evaporator ina heating mode. Further still, in some embodiments, the direct-expansionrefrigeration circuit is a primary direct-expansion refrigerationcircuit, or the system (e.g., 100 or 300) includes a primarydirect-expansion refrigeration circuit that uses the primary coolingcoil (e.g., 150 or 350) as a primary evaporator. In some embodiments,for example, the primary direct-expansion refrigeration circuit is aheat pump that both cools and heats the primary cooling coil (e.g., 150,350, or 1150) depending on whether cooling or heating of the space isdemanded (e.g., by at least one thermostat located within the space). Ina number of embodiments, when the system (e.g., 100, 300, or 1100) isoperating in a heating mode, the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) is turned off and when thesystem) is operating in a cooling mode, the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) is turned on.

Even further, in some embodiments, the secondary direct-expansionrefrigeration circuit evaporator coil (e.g., 160 or 360), the secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or340), or both, are not in the geothermal well field. Consequently, in anumber of embodiments, since the cost of drilling geothermal wells canbe based on the amount (e.g., tons) of cooling required, having thesecondary direct-expansion refrigeration circuit evaporator coil (e.g.,160 or 360), the secondary direct-expansion refrigeration circuitcondenser coil (e.g., 140 or 340), or both, not in the geothermal wellfield, can reduce the cost of installation of the geothermal well field,for example, in comparison with other geothermal alternatives thatprovide equivalent performance (e.g., cooling, humidity removal, orboth). Even further still, in various embodiments, using a geothermalheat sink or source can be beneficial (e.g., in addition to rejecting orobtaining heat at a preferable temperature) because the air conditioningor HVAC unit can be installed indoors (e.g., entirely or to a greaterextent) since there are no condensing (e.g., in a cooling mode) fansthat need access to outdoor air.

In various embodiments, the primary cooling coil (e.g., 150, 350, or1150) is larger, transfers more heat or enthalpy, or has more rows thanthe secondary cooling coil or secondary direct-expansion refrigerationcircuit evaporator coil (e.g., 160 or 360). In some embodiments, forexample, the primary cooling coil (e.g., 150, 350, or 1150) has at leastthree times as many rows as the secondary cooling coil or secondarydirect-expansion refrigeration circuit (evaporator coil (e.g., 160 or360). In various embodiments, for further examples, the primary coolingcoil (e.g., 150, 350, or 1150) has at least 1.5, 2, 2.5, 3.5, 4, 4.5 5,6, 7, or 8 times as many rows as the secondary cooling coil or secondarydirect-expansion refrigeration circuit (evaporator coil (e.g., 160 or360). Further, in particular embodiments, the primary cooling coil(e.g., 150, 350, or 1150) has six to eight rows. In other embodiments,the primary cooling coil (e.g., 150, 350, or 1150) has four to ten rows,four to twelve rows, six to ten rows, six to twelve rows, four or morerows, five or more rows, six or more rows, seven or more rows, eight ormore rows, or ten or more rows, as other examples. In comparison, insome embodiments, the secondary cooling coil or secondarydirect-expansion refrigeration circuit evaporator coil (e.g., 160 or360) has one row. Still further, in some embodiments, the heating coilor secondary direct-expansion refrigeration circuit condenser coil(e.g., 140 or 340) has one row. In other embodiments, however, asfurther examples, the secondary cooling coil or secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) evaporatorcoil (e.g., 160 or 360) has two or three rows, the heating coil (e.g.,140 or 340) or secondary direct-expansion refrigeration circuit (e.g.,125 or 325) condenser coil (e.g., 140 or 340) has two or three rows, ora combination thereof.

Even further, in various embodiments, the primary cooling coil (e.g.,150, 350, or 1150) transfers more heat (e.g., at design or maximumcapacity, or on average) than the secondary cooling coil or secondarydirect-expansion refrigeration circuit evaporator coil (e.g., 160 or360) transfers (e.g., at design or maximum capacity or on average). Forexample, in some embodiments, the primary cooling coil (e.g., 150, 350,or 1150) transfers more than twice as much heat at maximum capacity thanthe secondary cooling coil or secondary direct-expansion refrigerationcircuit evaporator coil (e.g., 160 or 360) transfers at maximumcapacity. In other embodiments, the primary cooling coil (e.g., 150,350, or 1150) transfers more than 1.5, 1.75, 2.25. 2.5. 3, 4, 5, 6, 7,8, 9, 10, or 12 times as much heat (e.g., at design or maximum capacityor on average) than the secondary cooling coil or secondarydirect-expansion refrigeration circuit evaporator coil (e.g., 160 or360) transfers (e.g., at design or maximum capacity or on average), asfurther examples.

In various embodiments (e.g., of a system for controlling temperatureand humidity within a space in a building) in which the space includesmultiple zones, (e.g., each of) the multiple zones include a (e.g., atleast one) zone direct-expansion refrigeration circuit, for example,that includes a zone compressor, a zone indoor air coil, and a zoneoutdoor heat exchanger, for example, among other things. In someembodiments, for example, one or more zone direct-expansionrefrigeration circuits are used instead of chilled beams in some or allof the zones. Further, in some embodiments, (e.g., each or at least one)zone direct-expansion refrigeration circuit is or includes a heat pumpthat both cools and heats the space (e.g., depending on whether coolingor heating is demanded by the thermostat), for example, that both coolsand heats a single zone of the multiple zones. Still further, inparticular embodiments, each zone outdoor heat exchanger is a geothermalheat exchanger. Even further, in certain embodiments, thedirect-expansion refrigeration circuit described herein, for example,that uses the geothermal heat sink as a geothermal condenser in acooling mode that uses the geothermal heat sink as an evaporator in aheating mode, or both, includes one or more of the zone direct-expansionrefrigeration circuits.

In various embodiments, the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) is energized, for example, under control ofthe system controller (e.g., 170 shown in FIG. 1), for instance, toensure that condensation does not occur during low airflow conditions onthe return air (e.g., 345 or 1145) side, for example, on the partition(e.g., 111 or 311), for instance, resulting from pressurization needs orvariable volume operation, by increasing the relative humidity enteringand leaving the return air (e.g., 345 or 1145) side of thedehumidification wheel (e.g., 130 or 330). In many embodiments, forexample, the supply airstream (e.g., 335 or 1135) is greater (e.g., involumetric flowrate) than the exhaust airstream (e.g., 315 or 1115), forexample, to pressurize the building, for instance, to preventinfiltration through the building exterior of (e.g., warm, humid, orboth) outdoor air into the space. In various embodiments, the flow ratescan be adjusted by changing the speed of the fans (e.g., 112, 312, 113,313 or a combination thereof), for example. Various embodimentsdescribed herein allow for a wide imbalance between the supply airstream(e.g., 335 or 1135) and the exhaust airstream (e.g., 315 or 1115)without causing (e.g., any or as much) condensation formation within theexhaust airstream or, in many embodiments, limiting dehumidificationperformance (e.g., passive dehumidification wheel performance).Moreover, in various embodiments, the system controller (e.g., 170) isconfigured to operate or energize the secondary direct-expansionrefrigeration circuit compressor (e.g., 120 or 320) to ensure thatcondensation does not occur during low airflow conditions on the returnair or exhaust airstream side resulting from pressurization needs orvariable volume operation. In a number of embodiments, condensation isavoided by decreasing the relative humidity entering and leaving theexhaust airstream (e.g., 315 or 1115) side of the dehumidification wheel(e.g., 130 or 330).

Still further, in some embodiments, the system (e.g., 100, 300, or 1100)includes a system controller (e.g., controller 170 shown in FIG. 1), forexample, in particular embodiments, configured to operate the secondarydirect-expansion refrigeration circuit compressor (e.g., 120 or 320)when (e.g., whenever) the system (e.g., 100, 300, or 1100) is operatingin a cooling mode. As used herein, a controller being “configured”, toperform one or more acts under one or more conditions means that thecontroller contains software that, when executed, or circuits that whenenergized, cause the controller to direct equipment to perform the oneor more acts when the one or more conditions occur. Further, as usedherein, a controller being “configured”, to perform one or more acts toaccomplish a particular result means that the controller containssoftware that, when executed, or circuits that when energized, cause thecontroller to direct the equipment in a manner that accomplishes theparticular result. Further still, as used herein, a controller being“configured”, to perform one or more acts to control a particularvariable means that the controller contains software that, whenexecuted, or circuits that when energized, cause the controller todirect the equipment in a manner that controls the particular variable.For example, in various embodiments, the system controller (e.g., 170)is configured to modulate cooling at the primary cooling coil (e.g.,150, 350, or 1150) to control temperature of the space when operating ina cooling mode, when operating in a dehumidification mode, or both.

Still further, in many embodiments, the system controller (e.g., 170) isconfigured to modulate cooling at the primary cooling coil (e.g., 150,350, or 1150) to control temperature of the supply airstream (e.g., 335or 1135) delivered to the space when operating in a cooling mode, whenoperating in a dehumidification mode, or both. In some embodiments, forexample, the temperature of the supply airstream (e.g., 335 or 1135)delivered to the space is limited to a minimum temperature (e.g., evenif the temperature of the space is greater than the thermostat setpoint) to avoid delivering air that is uncomfortably cold to the spaceor zones. Moreover, in some embodiments, the system controller (e.g.,170) is configured to modulate cooling at the primary cooling coil(e.g., 150, 350, or 1150) to control humidity, for example, absolutehumidity, or dew point, of the space or supply air when operating in acooling mode, when operating in a dehumidification mode, or both. Forexample, in some embodiments, the system controller (e.g., 170) isconfigured to modulate cooling at the primary cooling coil (e.g., 150,350, or 1150) to control absolute humidity level or dew point of thesupply airstream delivered to the space when operating in the coolingmode or the dehumidification mode. Further, in some embodiments, thesecondary cooling circuit (e.g., 125 or 325) is modulated (e.g., aswell) to control absolute humidity level or dew point of the supplyairstream delivered to the space, for example, when operating in thecooling mode or the dehumidification mode.

Even further, in some embodiments, when the supply airstream (e.g., 335or 1135) delivered to the space is uncomfortably cold, or approachessuch a temperature, the controller (e.g., 170) or software increases thespeed of the (e.g., passive) dehumidification wheel (e.g., 130 or 330)is increased (e.g., via a variable speed drive or variable speedcontrol) to increase the amount of sensible heat that is transferredfrom the return airstream (e.g., 345 or 1145) or the exhaust airstream(e.g., 315 or 1115) to the supply airstream (e.g., 335 or 1135) to heatthe supply airstream. Further, in some embodiments, the secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or340), when the secondary direct-expansion refrigeration circuit isoperated, raises the temperature of the return airstream, therebyproviding more reheat capacity for the modulating dehumidification wheel(e.g., 130 or 330) when in the reheat mode.

Conversely, in some embodiments, when the space is dry, the thermostatset point is exceeded (e.g., too warm when operating in a cooling mode),or both, the speed of the dehumidification wheel (e.g., 130 or 330) isdecreased (e.g., slowed or even stopped, for example, by controller 170)to decrease the amount of sensible heat that is transferred from theexhaust airstream (e.g., 315 or 1115) to the supply airstream (e.g., 335or 1135). In a number of embodiments, a controller (e.g., 170) or one ormore control algorithms (e.g., within controller 170) determine andcontrol the speed of the dehumidification wheel (e.g., 130 or 330), forexample, to control the amount of sensible heat, moisture, or both, thatis transferred from the return airstream (e.g., 345 or 1145) or theexhaust airstream (e.g., 315 or 1115) to the supply airstream (e.g., 335or 1135).

In a number of embodiments, the system controller (e.g., 170) isconfigured to modulate the rotational speed of the dehumidificationwheel (e.g., 130 or 330), for example, based on a measured temperatureof the supply airstream delivered to the space (e.g., of supply air337). Further, in a number of embodiments, the system controller (e.g.,170) is configured to modulate the rotational speed of thedehumidification wheel (e.g., 130 or 330) specifically to control thetemperature of the supply airstream delivered to the space. In variousembodiments, the system controller (e.g., 170) is configured to modulatethe rotational speed of the dehumidification wheel (e.g., 130 or 330)while the secondary circuit or secondary circuit compressor isoperating, for example. In a number of embodiments, heat from thesecondary condenser coil increases the impact that a change indehumidification wheel speed has on temperature of the supply air.

Even further, in various embodiments, the secondary direct-expansionrefrigeration circuit) compressor (e.g., 120 or 320) has avariable-speed drive (VSD). Even further still, in some embodiments, thesystem controller (e.g., 170) is configured to modulate speed of thesecondary direct-expansion refrigeration circuit compressor (e.g., 120or 320), for example, to adjust reheat capacity at the secondarycondenser coil (e.g., 140 or 340) when operating in a cooling mode, whenoperating in a dehumidification mode, or both. In various embodiments,the controller (e.g., 170) is “configured”, as used herein, withsoftware that, when executed, causes the controller to control thevarious items of equipment in the manner described. In otherembodiments, however, the controller can be “configured” through theconfiguration of the hardware that forms the controller. In someembodiments, for instance, operating the secondary direct-expansionrefrigeration circuit compressor (e.g., 120 or 320) at a higher speedwhile reducing cooling at the primary cooling coil (e.g., 150, 350), or1150, for instance, for system 300, by reducing chilled water flow tothe primary cooling coil (e.g., 350) or raising the chilled watertemperature, can increase the temperature of the supply airstream (e.g.,335) delivered to the space, in some embodiments and conditions, withouta corresponding increase in the moisture content of the supply airstreamor supply air (e.g., 337) delivered to the space.

Further still, in some embodiments, the secondary direct-expansionrefrigeration circuit compressor (e.g., 120 or 320) is a variablecapacity compressor and variable capacity drive or variable capacitycontrol (VCC) is used rather than, or in addition to, a variable-speeddrive. In various embodiments, compressor volume or displacement (e.g.,stroke) is modulated to control capacity, for example. Even furtherstill, in some embodiments, the system controller (e.g., 170) isconfigured to modulate capacity of the secondary direct-expansionrefrigeration circuit compressor (e.g., 120 or 320), for example, toadjust reheat capacity at the secondary condenser coil (e.g., 140 or340), for instance, when operating in a cooling mode, when operating ina dehumidification mode, or both. In different embodiments, VSD, VCC, orboth, are used. Moreover, in various embodiments, the system controller(e.g., 170) is configured to modulate the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) compressor (e.g., 120 or 320)(e.g., speed, capacity, or both), for example, to adjust reheat capacityat the secondary condenser coil (e.g., 140 or 340) when operating in acooling mode, when operating in a dehumidification mode, or both.

In a number of embodiments, the system controller (e.g., 170) isconfigured to lower the speed or capacity of the secondary directexpansion circuit compressor (e.g., 120 or 320) when the dew point orhumidity level in the space or supply air (e.g., 337) drops below asetpoint dew point or humidity level threshold, at least when supply airtemperature or space temperature, or both, are below a setpointtemperature threshold. In various embodiments, the system controller(e.g., 170) is configured to lower the rotational speed of thedehumidification wheel (e.g., 130 or 330), for example, and maintain thespeed or capacity of the secondary direct expansion circuit compressor(e.g., 120 or 320), when the dew point or humidity level in the space orsupply air (e.g., 337) drops below the setpoint dew point or humiditylevel threshold and the supply air temperature or space temperature (orboth) are above the temperature setpoint threshold.

Further, in a number of embodiments, the system controller (e.g., 170)is configured to increase the speed or capacity of the secondary directexpansion circuit compressor (e.g., 120 or 320) when the dew point orhumidity level in the space or supply air (e.g., 337) exceeds (e.g., thesame or a different) setpoint dew point or humidity level threshold, atleast when supply air temperature or space temperature, or both, areabove (e.g., the same or a different) setpoint temperature threshold.Moreover, in various embodiments, the system controller (e.g., 170) isconfigured to increase the rotational speed of the dehumidificationwheel (e.g., 130 or 330), for example, and maintain the speed orcapacity of the secondary direct expansion circuit compressor (e.g., 120or 320), when the dew point or humidity level in the space or supply air(e.g., 337) exceeds (e.g., the same or a different) setpoint dew pointor humidity level threshold and the supply air temperature or spacetemperature (or both) are below (e.g., the same or a different)temperature setpoint threshold.

In particular embodiments, the system controller (e.g., 170) isconfigured to operate the system (e.g., 100, 300, or 1100) in aneconomizer mode in which cooling at the primary cooling coil (e.g., 150,350, or 1150) is turned off. In some embodiments, for example, theprimary chiller or chillers that chill cooling water that passes throughthe primary cooling coil (e.g., 150 or 350), or the main chiller(s) asdescribed herein, are turned off and remain off during the economizermode. In other embodiments, the primary direct expansion refrigerationcircuit (e.g., 1122, as otherwise described herein, or other suchsystems), are turned off and remain off during the economizer mode. Invarious embodiments, however, during the economizer mode, at least whenhumidity levels warrant, the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) or compressor (e.g., 120 or 320) thereof isoperated to dehumidify the supply airstream (e.g., 335 or 1135) with thesecondary direct-expansion refrigeration circuit evaporator coil (e.g.,160 or 360), the (e.g., desiccant-based or passive) dehumidificationwheel (e.g., 130 or 330), or both. In some embodiments, the secondarycircuit is operated during the economizer mode (e.g., only) when outdoorair (e.g., 305) humidity is high enough that such dehumidification isnecessary or desirable. In such circumstances, the (e.g., smaller)secondary circuit compressor (e.g., 120 or 320) of the secondary circuit(e.g., 125 or 325) can be operated to provide the dehumidificationrather than operating the primary cooling circuit (e.g., chiller orchillers or primary direct expansion circuit or compressors). As usedherein, when a compressor or cooling is said to be turned off during aparticular mode of operation (e.g., the economizer mode), unlessindicated otherwise, the compressor or cooling is to remain off for theduration of that particular mode of operation.

Still further, in some embodiments, the system controller (e.g., 170) isconfigured to operate the system (e.g., 100, 300, or 1100) in apart-load mode in which cooling at the secondary cooling coil (e.g., 160or 360) is turned off and cooling at the primary cooling coil (e.g.,150, 350, or 1150) is modulated, for example, to dehumidify the supplyairstream (e.g., 335 or 1135) using the (e.g., desiccant-based)dehumidification wheel (e.g., 130 or 330). Even further, in someembodiments, the system controller (e.g., 170) is configured to operatethe system (e.g., 100, 300, or 1100) in a part-load or recirculationmode in which cooling at the primary cooling coil (e.g., 150, 350, or1150) is modulated down or off, and cooling the secondary cooling coil(e.g., 160 or 360) is modulated, for example, to dehumidify the supplyairstream (e.g., 335 or 1135), for instance, using the dehumidificationwheel (e.g., 130 or 330).

Further still, in a number of embodiments, the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) can providecooling when the chilled water plant or chiller is turned off, or whenthe primary direct expansion refrigeration circuit (e.g., 1122) isturned off, for example, due to temperature lockout or time of year. Insome cases, the chilled water plant may be active but the outdoor airsystem may be the only system that requires chilled water, for example,for dehumidification purposes. In such cases, especially when theambient conditions are cool, extremely cold chilled water may beproduced, for example, in low quantities, which may complicate thecontrol of the single chilled water coil. Accordingly, in someembodiments, the system controller (e.g., 170) is configured to operatethe system (e.g., 100, 300, or 1100) in a part-load mode in whichcooling at the primary cooling coil (e.g., 150, 350, or 1150) is turnedoff and the supply airstream (e.g., 335 or 1135) is cooled using thesecondary cooling coil (e.g., 160 or 360). In a number of embodiments,for example, cooling at the secondary cooling coil (e.g., 160 or 360) ismodulated, for example, by the system controller (e.g., 170) to controltemperature of the supply airstream (e.g., 335 or 1135), the space, orboth. In some embodiments, (e.g., when warranted by conditions) thesupply airstream (e.g., 335 or 1135) is dehumidified, for example, withthe secondary cooling coil (e.g., 160 or 360), the dehumidificationwheel (e.g., 130 or 330), or both, for example, in addition to orinstead of cooling with the secondary cooling coil (e.g., 160 or 360)when the primary cooling coil (e.g., 150, 350, or 1150) is turned off.Further, in certain embodiments, the system controller (e.g., 170) isconfigured to stop the (e.g., desiccant-based or passive)dehumidification wheel (e.g., 130 or 330), for example, when warrantedby conditions (e.g., when not needed to reduce humidity or to warm thesupply air). The dehumidification wheel (e.g., 130 or 330) can bestopped, for example, to avoid reheating the supply airstream (e.g., 335or 1135) after being cooled by the secondary cooling coil (e.g., 160 or360), for example, when operating in a mode where the primary coolingcoil (e.g., 150, 350, or 1150) is turned off.

Even further, in a number of embodiments, the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) can provide cooling,dehumidification, or condensation control during the startup andconstruction phase of a building. In certain embodiments, the systemcontroller (e.g., 170) is configured to operate and control (e.g.,modulate) the secondary direct-expansion refrigeration circuit (e.g.,125 or 325) to provide such cooling, dehumidification, and/orcondensation control specifically during the startup and constructionphase of the building. For example, in some embodiments, due tounconditioned areas, lack of finalized air balancing or controls, orboth, the secondary direct-expansion refrigeration circuit (e.g., 125 or325) can provide temporary cooling or dehumidification, for instance,during times when the space humidity is high or even uncontrollable.Accordingly, in some embodiments, the system controller (e.g., 170) isconfigured to operate and control (e.g., modulate) the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) to providetemporary cooling during times when the space humidity is high or evenuncontrollable, at least to design levels. Further, during such times,condensation can occur, for example, on the (e.g., passive)dehumidification wheel (e.g., 130 or 330), for instance, served by aprimary or chilled water system. In various situations, this can, forexample, damage the wheel or cause corrosion.

In a number of embodiments, the inclusion of the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325), which canraise the moisture-carrying capability of the return airstream (e.g.,345 or 1145) before the dehumidification wheel (e.g., 130 or 330),solves this problem under many conditions. Further, in particularembodiments, the system controller (e.g., 170) is configured to operateand control (e.g., modulate) the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) to prevent condensation, forexample, on the dehumidification wheel (e.g., 130 or 330) served by achilled water system, for instance, to avoid problems, for example,which can cause corrosion or damage the wheel. In various embodiments,the system controller (e.g., 170) is configured to operate and control(e.g., modulate) the secondary direct-expansion refrigeration circuit(e.g., 125 or 325) to raise the temperature of the return airstream(e.g., 345 or 1145) before the dehumidification wheel (e.g., 130 or330), for example, to prevent condensation on the dehumidification wheel(e.g., 130 or 330).

In some embodiments, the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) can be operated or modulated (e.g., by thesystem controller, for instance, 170) to deliver a warmer supply air(e.g., 337) temperature to the occupied space or active chilled beams,for example, to avoid over-cooling of the space by the primary airflowalone. When low dew points are desired, for example, colder air may berequired to be delivered to the dehumidification wheel (e.g., 130 or330) which can result in colder air leaving the dehumidification wheel.In some conditions, this reheat capability can be highly advantageous.In some embodiments, for example, the system controller (e.g., 170) isconfigured to operate the secondary direct-expansion refrigerationcircuit (e.g., 125 325) or compressor (e.g., 120 or 320), for example,to deliver a warmer supply air (e.g., 337) temperature to the occupiedspace or active chilled beams, for instance, to avoid over-cooling ofthe space by the primary airflow alone (e.g., when temperature,humidity, or both conditions warrant such operation). Further, incertain embodiments, the system controller (e.g., 170) is configured tomodulate the secondary direct-expansion refrigeration circuit (e.g., 125or 325) or compressor (e.g., 120 or 320) (e.g., speed or capacity), forexample, to deliver a warmer supply air (e.g., 337) temperature to theoccupied space or active chilled beams, for instance, to avoidover-cooling of the space by the primary airflow or to control coolingthereof.

In various embodiments, the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) or secondary compressor (e.g., 120 or 320)can be modulated down (e.g., reduced in speed or capacity), or eventurned off, when conditions within the space have a high sensible loadand low latent load, when cold air is desired from the system or unit,and when condensation on the return air (e.g., 345 or 1145) side leavingthe dehumidification wheel (e.g., 130 or 330) is not a concern, forexample. Under such conditions, cooling can be provided with the primarycooling coil (e.g., 150, 350, or 1150), for instance. Under suchconditions, the primary cooling coil (e.g., 150, 350, or 1150) may alsoprovide dehumidification, even though greater dehumidification mayresult if the secondary circuit were used. In some embodiments, forexample, the system controller (e.g., 170) is configured to turn off thesecondary direct-expansion refrigeration circuit (e.g., 125 325) orcompressor (e.g., 120 or 320) and provide cooling with the primarycooling coil (e.g., 150, 350, or 1150) when conditions within the spacehave a high sensible load and low latent load, when cold air is desiredfrom the unit, when condensation on the return air (e.g., 345 or 1145)side leaving the dehumidification wheel (e.g., 130 or 330) is not aconcern, or a combination thereof.

In particular embodiments, the system controller (e.g., 170) isconfigured to reduce the speed or capacity of the secondary compressor(e.g., 120 or 320) or reduce the capacity of the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) whenconditions within the space have a high sensible load and low latentload, when cold air is desired from the unit, when condensation on thereturn air side leaving the dehumidification wheel (e.g., 130 or 330) isnot a concern, or a combination thereof. These control strategies can bebeneficial, for example, under conditions that are relatively hot anddry. In a number of embodiments, the controller (e.g., 170) can modulatedown or turn off the secondary direct-expansion refrigeration circuit(e.g., 125 or 325) or compressor (e.g., 120 or 320), for example, inresponse to space temperature relative to one or more thermostatsetpoints, and one or more humidity or dew point measurements, forexample.

In many projects, for example, in many schools, there is a need ordesire to maintain space humidity during unoccupied hours. Further, in anumber of situations, the number of these hours can be substantial.Accordingly, various embodiments provide an unoccupied mode whereminimal outdoor air (e.g., 305), and thereby cooling load, is required.In a number of embodiments, under these conditions, the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) can beoperated to perform dehumidification, for example, in some embodiments,all of the dehumidification needs, without the need for operating theprimary chilled water, direct expansion (e.g., 1122), or heat pumpcircuit. In some embodiments, for example, the system controller (e.g.,170) is configured to operate or modulate the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) or compressor (e.g., 120 or320) to maintain space humidity during unoccupied hours or to provide anunoccupied mode where minimal outdoor air (e.g., 305), and therebycooling load, is required (e.g., or both). In a number of embodiments,the system controller (e.g., 170) is configured to operate or modulatethe secondary direct-expansion refrigeration circuit (e.g., 125 or 325)or compressor (e.g., 120 or 320) (e.g., during unoccupied periods, underappropriate conditions, or both) to perform dehumidification (e.g., allof the dehumidification needs), for instance, without operating (e.g.,while turning off and leaving turned off) the primary cooling coil(e.g., 150, 350, or 1150) (e.g., chilled water, direct expansion, orheat pump circuit).

In various situations where the primary cooling coil (e.g., 150 or 350)or circuit (e.g., chiller or chillers) is operated to providedehumidification, however, under such conditions, other cooling at thespace may not be needed so the chiller may be operated at a low load andproblems can be encountered maintaining a desired or consistent coolingwater temperature. For example, in some conditions where a cooling watertemperature of 42 degrees was desired, the chilled water temperaturefluctuated between 36 and 40 degrees, as examples, which caused problemscontrolling the air temperature from the primary cooling coil. In anumber of embodiments that have a secondary (e.g., refrigeration)circuit, however, the primary cooling coil (e.g., 150 or 350) is notused at all under certain low-cooling-demand circumstances or when onlydehumidification is required, and air temperature can be easier tocontrol, can be controlled more precisely, or both.

Still further, in a number of embodiments, conditions can exist wherethe primary cooling coil (e.g., 150, 350, or 1150) (e.g., chiller orchillers or direct expansion system, for instance, 1122) is needed tocool outdoor air (e.g., 305) introduced to the space but other coolingat the space (e.g., chilled beams or zone direct expansion units, suchas geothermal units) are not needed to provide further cooling. Variousembodiments provide cooling of outdoor air (e.g., 305) at the primarycooling coil (e.g., 150, 350, or 1150) under such circumstances withoutproviding other cooling at the space. Even further, in some embodiments,the system (e.g., 100, 300, or 1100) or unit can be operated in anunoccupied mode. In particular embodiments, for example, air isrecirculated within the system or unit in an unoccupied mode. Moreover,in various embodiments, an unoccupied mode can include, at least undercertain circumstances, using the secondary (e.g., direct-expansionrefrigeration) circuit alone (i.e., without cooling at the primarycooling coil (e.g., 150, 350, or 1150). In various applications, lesssensible cooling is required when the building is unoccupied, but somelevel of dehumidification, (e.g., less than when the building isoccupied) may be required or desirable. In a number of embodiments, thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325) canprovide such dehumidification.

An example of a dehumidification wheel (e.g., 130 or 330), as usedherein, is a passive dehumidification wheel. As used herein a “passivedehumidification wheel” is a dehumidification wheel that transfers asignificant quantity of moisture from the supply airstream (e.g., 335 or1135) chilled by the primary cooling coil (e.g., 150, 350, or 1150) tothe exhaust airstream (e.g., 315 or 1115) without the exhaust airstreambeing heated to promote regeneration of the dehumidification wheel.Dehumidification wheels 130 and 330 are passive dehumidification wheelsin many embodiments. Further, as used herein, the “passivedehumidification wheel” (e.g., 130 or 330) is one that provides moistureremoval from the (e.g., saturated or near saturated) supply airstream(e.g., 335 or 1135) leaving the primary (e.g., 150, 350, or 1150) orsecondary cooling coil (e.g., 160 or 360) when operated, with or withoutthe modest added heat provided, for example, by the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) condenser coil(e.g., 140 or 340) located in the return airstream (e.g., 345 or 1145).In many embodiments, for example, the adsorbed moisture contained withinthe passive (e.g., desiccant) wheel is removed (i.e., regenerated), orcan be, by using the lower relative humidity air contained within thereturn or exhaust airstream (e.g., 315 or 1115) alone.

In many embodiments, the dehumidification wheel (e.g., 130 or 330)regenerates when removing moisture from the (e.g., saturated or nearsaturated) supply airstream (e.g., 335 or 1135) with exhaust air (e.g.,315 or 1115) returned from the space that is at a temperature below 95degrees F. In other embodiments, the dehumidification wheel (e.g., 130or 330) regenerates when removing moisture from the (e.g., saturated ornear saturated) supply airstream (e.g., 335 or 1135) with exhaust air(e.g., 315 or 1115) returned from the space that is at a temperaturebelow 100, 97, 93, or 90 degrees F., as other examples. Further, in manyembodiments, the dehumidification wheel (e.g., 130 or 330) regenerateswithout the regenerating airstream (e.g., exhaust airstream 335 or 1135)having been heated with a burner that burns a fuel. Further still, inmany embodiments, the dehumidification wheel (e.g., 130 or 330)regenerates without the regenerating airstream (e.g., exhaust airstream335 or 1135) having been heated to a temperature that exceeds 95 degreesF. Still further, in various embodiments, the dehumidification wheel(e.g., 130 or 330) regenerates without the regenerating airstream (e.g.,exhaust airstream 335 or 1135) having been heated to a temperature thatexceeds 100, 97, 93, or 90 degrees F., as other examples. Even further,in many embodiments, heat from the secondary condenser coil (e.g., 140or 340) is the only heat added to the return air (e.g., 345 or 1145)after the return air leaves the space but before the return air is usedto regenerate the dehumidification wheel (e.g., 130 or 330). In fact, invarious embodiments, no heat other than the heat from the secondarycondenser coil (e.g., 140 or 340) is added to the return air (e.g., 345or 1145) between the time that the return air leaves the space and thereturn air is used to regenerate the dehumidification wheel (e.g., 130or 330). In further embodiments, no substantial heat other than the heatfrom the secondary condenser coil (e.g., 140 or 340) is added to thereturn air (e.g., 345 or 1145) between the time that the return airleaves the space and the return air is used to regenerate thedehumidification wheel (e.g., 130 or 330). In this context,“substantial” means enough to raise the temperature of the air by morethan five degrees. In other embodiments, no heat other than the heatfrom the secondary condenser coil (e.g., 140 or 340) is added to thereturn air (e.g., 345 or 1145) between the time that the return airleaves the space and the return air is used to regenerate thedehumidification wheel (e.g., 130 or 330) that is enough heat to raisethe temperature of the return air by more than 4, 6, 8, 10, 12, or 15degrees, as other examples.

Further, in a number of embodiments, there are times when it isbeneficial (e.g., for higher energy efficiency during part loadconditions) to operate the system or unit (e.g., 100, 300, or 1100)without operating the secondary direct-expansion refrigeration circuit(e.g., 125 or 325), or the compressor thereof (e.g., 120 or 320). Stillfurther, in some embodiments, the system (e.g., 100, 300, or 1100),unit, or controller (e.g., 170) is configured (e.g., programmed) tooperate the system or unit without operating the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) or compressor(e.g., 120 or 320), cooling the supply airstream (e.g., 335 or 1135) atthe secondary direct-expansion refrigeration circuit evaporator coil orsecondary cooling coil (e.g., 160 or 360), or heating the exhaustairstream (e.g., 315 or 1115) at the secondary direct-expansionrefrigeration circuit condenser coil or heating coil (e.g., 140 or 340),for example, under part load conditions. In many embodiments, thesystem, unit, or controller is configured to turn off the secondarycircuit when it is beneficial to do so (e.g., when dehumidification oradditional dehumidification from the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) or secondary cooling coil(e.g., 160 or 360) and dehumidification wheel (e.g., 130 or 330) is notneeded or desirable). In various embodiments, control algorithmsdetermine when the secondary direct-expansion refrigeration circuit(e.g., 125 or 325) is on or, in some embodiments, is modulated, duringcooling or dehumidification modes (or both).

Further still, where passive dehumidification wheels (e.g., 130 or 330)are described herein, other embodiments, an active dehumidificationwheel is another alternative that is contemplated. Adding significantadditional regenerative heat can, however, among other things, reduce oreliminate the benefit of the recovery wheel (e.g., 110 or 310), at leastin a number of the equipment configurations described herein, or in somecircumstances. For this and other reasons, including the need foradditional regenerative heat for an active dehumidification wheel,various embodiments described herein use a passive dehumidificationwheel (e.g., 130 or 330) rather than an active dehumidification wheel.As mentioned, however, other embodiments may differ.

In many embodiments where the primary cooling coil, for instance, 150 or350, is cooled with chilled water, the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) can be used to deliver colderair than would be possible with a chilled water system alone due to thetemperature limitation of the chilled water available. In particularembodiments, this allows air that is colder or that has a lower dewpoint (or both) to be produced and delivered, for example, inconjunction with the dehumidification wheel (e.g., 130 or 330). Asdescribed, in chilled water systems, the minimum temperature that theair leaving the cooling coil (e.g., 150 or 350) can reach has beenlimited by how cold the chilled water can be produced using traditionalchiller performance limitations. As a result, the minimum temperatureand the amount of humidity that can be removed from the outdoor air(e.g., 305) are limited. Lower levels of humidity in the supply air(e.g., 337), however, can be beneficial in some situations, for example,where chilled beams are used. In some embodiments, for example, thesystem controller (e.g., 170) is configured to operate the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) to delivercolder air than would be possible with a chilled water system alone, forexample, due to the temperature limitation of the chilled wateravailable. In various embodiments, the system controller (e.g., 170) isconfigured to operate the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) to allow air that is colder or that has alower dew point (or both, in a number of embodiments) to be produced anddelivered, for example, in conjunction with the dehumidification wheel(e.g., 130 or 330, for instance, in comparison with a system havingchilled water that does not have a secondary direct expansion circuit),for example, as shown in FIGS. 2 and 4.

In many situations, it is beneficial for components of the system (e.g.,air conditioning or HVAC, for instance, 100, 300, or 1100) to be locatedwithin the building rather than outdoors. In a number of embodiments,the secondary circuit (e.g., 125 or 325) is (e.g., entirely) locatedwithin the building. For instance, the second stage DX evaporator coil(e.g., 160 or 360) is matched with the condenser coil (e.g., 140 or 340)contained within the building exhaust airstream (e.g., 315 or 1115). Inthis configuration, a remote condensing section, outside the building,is typically not required for the secondary circuit (e.g., 125 or 325).When chilled water is used for the first stage cooling coil (e.g., 150or 350), chilled water must be supplied, but refrigerant lines to aremote condensing section, outside the building, is typically notrequired for the first stage cooling coil (e.g., 150 or 350).

When the first cooling stage (e.g., serving primary cooling coil 150 or350) is also designed to be a direct expansion circuit or heat pump, aremote condensing section outside the building can be used, in a numberof embodiments, so that a high volume of outdoor air can be pulledacross the condensing coil and ejected to the outdoors. This approach,however, requires refrigerant lines to the remote condensing sectionoutside the building, which typically must be installed, connected,tested, and charged at the job site. In addition, in many installations,outdoor space suitable for the remote condensing section outside thebuilding may be in short supply. In some embodiments, water sourcecondensing sections are employed for the first stage cooling (e.g., atprimary coil 150 or 350), and can offer certain performance advantagesover air cooled condensing sections by providing a more moderatetemperature heat sink or source, especially when heat pump capability isutilized. Using a water source approach, however, requires drillingeither one or more geothermal wells or installing a cooling tower andinstalling a water loop, both of which require space that may not beavailable and may increase the cost of installation.

As illustrated in FIG. 11, an alternate approach in some embodimentsutilizes a first stage or primary direct expansion cooling circuit(e.g., 1122), for example, in addition to the (e.g., integrated) secondstage DX cooling circuit (e.g., 125). In many embodiments, the condensercoil (e.g., 140 or 340) for the secondary cooling circuit (e.g., 125 or325) is located within the return air or exhaust airstream (e.g., 315 or345 shown in FIG. 3, or 1115 or 1145 in FIG. 11) from the conditionedspace as described herein. In various embodiments, the unit or system(e.g., 1100) includes a primary direct-expansion refrigeration circuit(e.g., 1122) that includes the primary cooling coil (e.g., 1150) whichacts as a primary evaporator when operating in a cooling mode. In manyembodiments, the primary direct-expansion refrigeration circuit (e.g.,1122) also includes a primary condensing coil (e.g., 1104) which acts asa condenser when operating in the cooling mode, and at least one primarycompressor (e.g., 1120). In a number of embodiments, the exhaustairstream (e.g., 1115) passes through the primary condensing coil (e.g.,1104, as shown). In various embodiments (e.g., system 1100), the returnair (e.g., 1145) of the exhaust airstream (e.g., 1115) passes firstthrough the secondary circuit condenser coil (e.g., 140), then throughthe (e.g., desiccant-based) dehumidification wheel (e.g., 130), thenthrough the recovery wheel (e.g., 110), and then through the primarycondensing coil (e.g., 1104).

In some embodiments, the first stage direct expansion cooling circuit(e.g., 1122) is (e.g., totally) integrated within the enclosure (e.g.,101) of the system or unit (e.g., 1100). In the embodiment shown,condenser coil 1104 for first stage or primary circuit 1122 (e.g., ofcooling) is installed within exhaust air outlet section 1101 of system1100 allowing the existing exhaust air fan 1112 to also function as thecondenser fan. The enhanced static pressure capability associated withsuch an exhaust/condenser fan (e.g., 1112), in various embodiments,provides performance advantages over conventional, low static capabilitycondenser fans. These advantages can include, for example, the abilityto use a deeper, more efficient condensing coil (e.g., 1104) withincreased rows, tighter fins, more capacity, or a combination thereof,as examples. Another advantage, in some embodiments, is improvedperformance during frosting conditions when the first cooling stage(e.g., 1122) is operated as a heat pump (e.g., heating primary coil 1150to heat the space).

In other embodiments, both an outdoor air condensing coil and acondensing coil in the return air are used. In some embodiments,however, this requires an outdoor condensing unit, with some or all ofthe concerns described herein. In other embodiments, outdoor airdelivered to the unit or enclosure (e.g., 101, for example, deliveredwith supply air 335 or 1135) feeds the outdoor air condensing coil,before joining the exhaust airstream (e.g., 315 or 1115). In manyembodiments, the secondary circuit (e.g., 125), dehumidification wheel(e.g., 130), or both, make an integrated first stage direct expansioncooling circuit (e.g., 1122) more feasible or function better, at leastunder certain conditions. In some other configurations, the amount ofheat rejected from the condenser coil (e.g., analogous to 1104) cannotbe absorbed by the exhaust air (e.g., analogous to 1115) leaving thesystem without resulting in unacceptably high condensing temperatures.Extreme condensing temperatures can substantially reduce the compressorcooling output and efficiency and can also reduce the life of thecompressor (e.g., analogous to 1120). With many prior art systems (e.g.,shown in FIGS. 2 and 4), all of the cooling input required to achievethe necessary cooling and dehumidification is typically accomplishedusing a single, stage 1 cooling circuit. As a result, the temperatureleaving this stage 1 cooling coil needs to be low enough to satisfy thatneed (e.g., in conjunction with the dehumidification wheel) to deliverthe desired dew point. Stated more simply, the air temperature leavingthe stage 1 cooling coils of the prior art must be much lower than thatleaving the stage 1 coil (e.g., 1150) of many embodiments describedherein (e.g., system 1100), since the integrated second stage coil(e.g., 160) included in such embodiments provides the final, low dewpoint cooling necessary.

Since system 1100, for example, can deliver an air temperature off ofthe stage 1 cooling circuit (e.g., leaving primary coil 1150, cooled byprimary DX circuit 1122), that is less cold, a higher suctiontemperature can be used at the stage 1 coil (e.g., 1150), whileproviding the same performance as the systems in FIGS. 2 and 4, forexample. This increases the operating efficiency of the primary circuitcompressor(s) (e.g., 1120 in FIG. 11) and helps to offset the decreasein system efficiency associated with operating at a higher condensingtemperature (e.g., at coil 1104). Further, in many embodiments, thetotal cooling load requirement is reduced by the addition of the stage 2cooling circuit (e.g., 125) and since (e.g., in system 1100) thecondensing needs are satisfied by the return air (e.g., 1145) from thespace, the stage 1 cooling circuit (e.g., 1122) can be smaller, in anumber of embodiments, requiring fewer tons than many prior art systems(e.g., 200 shown in FIGS. 2 and 4).

Further, in many configurations (e.g., 200), the air temperatureexhausted from the system is cooler than the outdoor air temperaturesince the recovery system is not 100% efficient. Further still, in manyembodiments, the purge and seal leakage airflow volumes, often thoughtof as parasitic energy losses, increase the return airflow volumeleaving the conditioned space or through the primary condenser coil(e.g., 1104). This increase in “condenser airflow” and reduction in“condenser airflow temperature” can help to increase the operatingefficiency of system 1100, for example. When combined with the benefitof a higher suction temperature and smaller stage 1 cooling circuitpreviously described, the condensing capacity requirement can be reducedlow enough, under many conditions, to allow the exhaust airflow volume(e.g., at 1115 or through coil 1104) to be used for rejection of theheat from the primary circuit (e.g., 1122), thereby eliminating theneed, in other configurations or embodiments, for a remote condensingsection.

Still further, in some embodiments, for instance, during times ofextreme outdoor temperatures, the exhaust air temperature, airflow, orboth (e.g., at exhaust air outlet section 1101 or condenser coil 1104),in many US climatic conditions is not adequate to maintain a desirablecondensing (head) pressure (e.g., within primary direct expansioncircuit 1122) and can cause high pressure trips or premature compressor(e.g., 1120) failure, in particular embodiments, even with the benefitsdescribed herein. In some circumstances, for example, the exhaust airtemperature can be too high, the exhaust airflow (e.g., at 1115 orthrough coil 1104) can be too low, or a combination thereof. Someembodiments address this potential problem by monitoring the condensingpressure (e.g., within primary direct expansion circuit 1122, forexample, monitoring using the system controller, for example, 170), andimplementing a change that increases the system condensing side capacitywhen necessary.

An example of a way of increasing condensing side capacity (e.g., underextreme conditions) is to “flash evaporate” a fine water mist ahead(i.e., upstream) of the condenser coil (e.g., between recovery wheel 110and condenser coil 1104 in FIG. 11). This can substantially lower theair temperature entering the coil, thereby increasing condensingcapacity. Another way to increase condensing capacity is to useevaporative cooling pads in place of the flash evaporation mist (e.g.,between recovery wheel 110 and condenser coil 1104). As used herein,flash evaporation of a fine water mist, and evaporative cooler pads, areboth examples of evaporative cooling. Yet another way to increasecondensing capacity is to add outdoor air to the exhaust air, forexample, upstream of the condensing coil (e.g., between recovery wheel110 and condenser coil 1104) to increase condenser airflow. In someembodiments, such added outdoor air is cooled with evaporative cooling(e.g., in different embodiments, before or after being combined withreturn air). Further, in some embodiments that include evaporativecooling for cooling condenser air (e.g., for condenser 1104), theevaporative cooling is used even when outdoor temperatures are notextreme, but when cooling is demanded, to reduce electricity consumption(e.g., by compressor 1120) or increase capacity of the direct expansionrefrigeration circuit (e.g., 1122), or both. In certain embodiments,however, evaporative cooling can be turned off (e.g., by the systemcontroller, for example, 170) when humidity or dew point (e.g., ofoutdoor air, return air, or both) exceeds a (e.g., set) threshold.

Certain embodiments provide variable refrigerant flow (VRF), include orare used as a dedicated outdoor air supply (e.g., subsystem) ordedicated outdoor air system (DOAS), or both. Variable refrigerant flowsystems, in a number of embodiments, can provide simultaneous heatingand cooling to different zones within one or more buildings, forexample. Like a number of embodiments of heat pump systems, however,many VRF systems do not handle raw outdoor air very well. Many VRFsystems can be highly efficient in processing sensible (temperature)loads, but, in many cases, are less efficient or effective at handlingthe latent loads, for example, associated with high density spaces, forinstance, like school classrooms. As a result, some embodiments serveVRF systems with a dedicated outdoor air system. In a number ofembodiments, for example, VRF systems are served by an outdoor airsystem (e.g., 1100) that can decouple the latent load from the VRF roommodules so that the zone VRF coils can handle sensible only loads andoperate with higher suction temperatures. This can increase overallsystem efficiency, for example. Further, removing the latent load fromthe VRF modules can reduce the cooling capacity requirement andtherefore size of the unit required in each classroom, for example. Thiscan provide many system design advantages under various circumstances.

Still further, in many embodiments, installing smaller VRF units candecrease the installation cost due, for example, to the smaller unitsand refrigerant lines. Even further, in some embodiments, a smaller maincondensing unit can be employed. Even further still, in particularembodiments, condensate management can be reduced or eliminated sincethe latent load is partially or fully handled by the DOAS (e.g., 1100).Moreover, in many embodiments, fewer pounds of refrigerant are beingpumped through the building, addressing one substantial concernregarding this technology should there be a refrigerant leak.Additionally, one challenge facing VRF systems is efficiently deliveringthe necessary heating capacity in colder climates. In some embodiments,rotational speed of the VRF compressor is increased to increase theheating output at low ambient temperatures, for example, but limitationsstill exist and it would be highly beneficial to increase the heatingoutput available as well as the efficiency or coefficient ofperformance.

In various embodiments, two effective ways of increasing the heatingcapacity available to the conditioned spaces are to minimize the heatingcapacity required by the DOAS to condition the outdoor air and toallocate a sizeable and more effective “outdoor coil” for the VRF systemwhere a substantial airflow can be used as a heat source (e.g., cooledto obtain heat to add to the space). Some embodiments (e.g., system1100) can provide both of these enhancements. As an example, assume aschool has a wing including 10 classrooms and needs 3,000 cfm of outdoorair for ventilation purposes. Decoupling the space latent load from theindividual room VRF modules, in this example, allows classroom units,operating to handle the sensible cooling load only, to be sized for 2tons each (24,000 BTUs). A conventional DOAS (e.g., system 200 shown inFIG. 2) employing a total energy recovery wheel (e.g., 210) wouldrequire approximately 16 tons of cooling input for this example toprocess the 3,000 cfm of outdoor air from a condition of 95 degrees F.DB and 78 degrees F. WB to deliver the 50-grain supply air humiditycondition required to handle both the outdoor air and spacedehumidification load. In contrast, in a number of embodiments (e.g.,1100) where the primary condenser coil (e.g., 1104) for the first stagecircuit (e.g., 1122) is installed within the exhaust air outlet section(e.g., 1101), the primary or stage 1 cooling circuit (e.g., 1122) onlyrequires 10 tons of cooling input. As a result, the total cooling forthe school wing can be achieved with only 30 tons in this example.

Now the same school operating during the winter with the outdoor airbeing 0 degrees F. DB needs 23,000 BTUs of heat for each classroom tomaintain the set point of 70 degrees F. DB. The DOAS can deliver air toeach room at 85 degrees F. DB providing 4,860 BTUs of heat so each VRFmodule must deliver the remaining 18,140 BTUs. At 0 degrees F. DB, thetypical VRF module rated at 2 tons with an outdoor condensing unit canonly deliver 16,000 BTUs when the outdoor VRF condensing unit cannotpull heat from any other zone. As a result, the spaces would not haveadequate heating capacity. In contrast, with certain embodiments (e.g.,system 1100 shown in FIG. 11), the stage 1 cooling circuit condensingcoil (e.g., 1104) is installed within the exhaust air section (e.g.,1101) of the DOAS instead of utilizing an outdoor condensing unit. Invarious embodiments, this coil, whether outdoors or in the exhaust airsection (e.g., the latter being shown in FIG. 11), serves as acondensing coil when cooling and an evaporator coil when heating. On a0-degree F DB day, the air over the evaporator coil (e.g., 1104) in theexhaust air section (e.g., 1101), in this example, is in the range of 15degrees F. DB since the recovery device is not 100% efficient. Thisprovides approximately 4,000 cfm of exhaust air from the dual wheel(e.g., 110 and 130) energy recovery system at the 15-degree F DB thatpasses across the VRF evaporator coil and functions as an effective heatsource to allow the main VRF condensing section to operate moreefficiently.

In this example, adding the evaporator load associated with the 4,000cfm of air at 15 degrees F. DB with the evaporator load of the main VRFcondensing section allows for a substantial increase in heating outputat the VRF modules installed in each classroom. In this example, theheating output from a 2-ton module would be increased from approximately16,000 BTUs to the 18,140 BTUs needed. Likewise, a similar coolingseason performance enhancement is recognized in this school example whenthe condenser (e.g., 1104) in the exhaust airstream (e.g., section 1101)processes air at approximately 90 degrees F. DB as opposed to theambient 95 degrees F. DB condition is combined with the main VRFcondensing section. Further, in many embodiments, the stage 2 coolingcircuit (e.g., 125), that handles the final, lower air temperaturecooling function, allows the stage 1 cooling circuit (e.g., 1122) tooperate at a higher suction temperature and to deliver air that is lesscold. In various embodiments, this provides an excellent match with theVRF system as it operates more effectively when under these conditions.With the DOAS typically requiring 40% of the total system coolingcapacity or more, off-loading approximately 25% of the DOAS coolingcapacity requirements on to the stage 2 cooling circuit (e.g., 125)handled by a designated compressor (e.g., 120) that is not part of theVRF grid is a significant advantage in a number of embodiments. Forexample, this allows for a smaller main VRF condensing section to beutilized and reduces the size of the refrigerant lines required as wellas the quantity of refrigerant required.

In a number of embodiments, a unit or system (e.g., for controllingtemperature and humidity within a space in a building) includes arecovery wheel, a (e.g., desiccant-based) dehumidification wheel, and aprimary direct-expansion refrigeration circuit. FIG. 11 provides anexample, system 1100. In various embodiments, the primarydirect-expansion refrigeration circuit (e.g., 1122) includes, forexample, at least one primary circuit compressor (e.g., 1120), a primarycircuit evaporator coil (e.g., 1150), and a primary circuit condensercoil (e.g., 1104). Further, in a number of embodiments, the system formsa supply airstream (e.g., 1135), for instance, that passes outdoor airfirst through the recovery wheel (e.g., 110), then through the primarycircuit evaporator coil (e.g., 1150), then through the dehumidificationwheel (e.g., 130), and then to the space. Still further, in variousembodiments, the system forms an exhaust airstream (e.g., 1115), forexample, that passes return air (e.g., 1145) from the space firstthrough the dehumidification wheel (e.g., 130), then through therecovery wheel (e.g., 110), and then through the primary circuitcondenser coil (e.g., 1104).

Some such embodiments (e.g., as shown in FIG. 11) further include asecondary direct-expansion refrigeration circuit (e.g., 125), forinstance, that includes a secondary circuit compressor (e.g., 120), asecondary circuit evaporator coil (e.g., 160), and a secondary circuitcondenser coil (e.g., 140). Moreover, in a number of embodiments, thesupply airstream (e.g., 1135) passes the outdoor air first through therecovery wheel (e.g., 110), then through the primary circuit evaporatorcoil (e.g., 1150), then through the secondary circuit evaporator coil(e.g., 160), then through the dehumidification wheel (e.g., 160), andthen to the space. Further, in particular embodiments, the exhaustairstream (e.g., 1115) passes the return air (e.g., 1145) from the spacefirst through the secondary circuit condenser coil (e.g., 140), thenthrough the dehumidification wheel (e.g., 140), then through therecovery wheel (e.g., 110), and then through the primary circuitcondenser coil (e.g., 1104). Even further, in particular embodiments,the primary circuit evaporator coil (e.g., 1150) has at least threetimes as many rows as the secondary circuit evaporator coil (e.g., 160),for example.

In certain embodiments, the recovery wheel (e.g., 110) is a total energyrecovery wheel that includes a desiccant coating, the recovery wheeltransfers sensible heat between the outdoor air of the supply airstream(e.g., 1135) and the exhaust airstream (e.g., 1115), the recovery wheeltransfers moisture between the outdoor air of the supply airstream andthe exhaust airstream, or a combination thereof. Further, in particularembodiments, the (e.g., desiccant-based) dehumidification wheel (e.g.,130) is a passive dehumidification wheel, the system further includes asupply fan (e.g., 1113) located in the supply airstream (e.g., 1135)that moves the outdoor air to the space, the system further includes anexhaust fan (e.g., 1112) located in the exhaust airstream (e.g., 1115)that moves the return air from the space, or a combination thereof.Still further, in a number of embodiments, the system (e.g., 1100)includes a partition (e.g., 111), for example, between the supplyairstream (e.g., 1135) and the exhaust airstream (e.g., 1115), therecovery wheel (e.g., 115) is located in a first opening (e.g., 601shown in FIG. 6) in the partition (e.g., 111 or 311), thedehumidification wheel is located in a second opening (e.g., 602 shownin FIG. 6) in the partition, at least adjacent to the partition (e.g.,111 or 311), the supply airstream (e.g., 1135) and the exhaust airstream(e.g., 1115) travel in substantially parallel directions, at leastadjacent to the partition, the supply airstream and the exhaustairstream travel in substantially opposite directions, and the system(e.g., 1100) further includes an enclosure (e.g., 101) that contains therecovery wheel (e.g., 110), the (dehumidification wheel (e.g., 130), theat least one primary circuit compressor (e.g., 1120), the primarycircuit evaporator coil (e.g., 1150), and the primary circuit condensercoil (e.g., 1104), at least part of the supply airstream (e.g., 1135),at least part of the exhaust airstream (e.g., 1115), and the partition(e.g., 111).

Even further, in some embodiments, the system (e.g., 1100, for instance,as shown) further includes, within the enclosure (e.g., 101), thesecondary direct-expansion refrigeration circuit (e.g., 125), forexample, including the secondary circuit compressor (e.g., 120), thesecondary circuit evaporator coil (e.g., 160), the secondary circuitcondenser coil (e.g., 140), or a combination thereof. In variousembodiments (e.g., of a unit or system), the primary direct-expansionrefrigeration circuit (e.g., 1122) is a heat pump, for example, thatboth cools and heats the primary circuit evaporator coil (e.g., 1150)depending on whether cooling or heating of the space is demanded.

Further still, in some embodiments, the unit or system (e.g., forcontrolling temperature and humidity within a space in a building)includes an evaporative cooler (not shown), for example, that precoolsair entering the primary circuit condenser coil (e.g., 1104 shown inFIG. 11). In particular embodiments, for instance, the evaporativecooler is located between the recovery wheel (e.g., 110) and the primarycircuit condenser coil (e.g., 1104). Still further, in a number ofembodiments, the exhaust airstream (e.g., analogous to 1115) passesthrough the evaporative cooler. Even further, in some embodiments,supplemental outdoor air is added to the exhaust airstream. Inparticular embodiments, for example, the supplemental outdoor air passesthrough the evaporative cooler. Still further, in certain embodiments,the supplemental outdoor air passes through the primary circuitcondenser coil, for instance, after the supplemental outdoor air passesthrough the evaporative cooler. Even further still, in some embodiments,the supplemental outdoor air is added to the exhaust airstream betweenthe recovery wheel and the primary circuit condenser coil.

Some embodiments (e.g., of a system for controlling temperature andhumidity within a space in a building, for instance, as describedherein) include a variable refrigerant flow subsystem (not shown), forexample, serving multiple zones within the space. In a number ofembodiments, for example, each of the multiple zones includes a fan coilunit of the variable refrigerant flow subsystem, and the supplyairstream (e.g., described herein) provides a dedicated outdoor airsupply (DOAS) that serves the variable refrigerant flow subsystem. Aparticular example is a system (e.g., for controlling temperature andhumidity within a space in a building) that includes a variablerefrigerant flow subsystem and a dedicated outdoor air supply subsystemthat includes, a recovery wheel, a (e.g., desiccant-based)dehumidification wheel, a primary cooling coil, and at least onecondenser coil. System 1100, shown in FIG. 11, is an example of such adedicated outdoor air supply subsystem. In a number of embodiments, thevariable refrigerant flow subsystem includes multiple fan coil unitsserving multiple zones within the space. Further, in variousembodiments, the dedicated outdoor air supply subsystem (e.g., 1100)serves the multiple zones. Still further, in many embodiments, thededicated outdoor air supply subsystem forms a supply airstream (e.g.,1135) that passes outdoor air first through the recovery wheel (e.g.,110), then through the primary cooling coil (e.g., 1150), then throughthe dehumidification wheel (e.g., 130), and then to the space. Furtherstill, in various embodiments, the dedicated outdoor air supplysubsystem (e.g., system 1100) forms an exhaust airstream (e.g., 1115)that passes return air (e.g., 1145) from the space through thedehumidification wheel (e.g., 130) and then through the recovery wheel(e.g., 110), for instance, as shown. Even further, in a number ofembodiments, the exhaust airstream (e.g., 1115) also passes through theat least one condenser coil (e.g., 140 or 1104).

In some embodiments (e.g., 1100), the dedicated outdoor air supply(e.g., subsystem) further includes a secondary direct-expansionrefrigeration circuit (e.g., 125), for example, that includes asecondary circuit compressor (e.g., 120), a secondary circuit evaporatorcoil (e.g., 160), and a secondary circuit condenser coil (e.g., 140).Further, in some embodiments, the at least one condenser coil (e.g.,described above) includes the secondary circuit condenser coil (e.g.,140). Still further, in some embodiments, the exhaust airstream (e.g.,1115) passes the return air (e.g., 1145) from the space first throughthe secondary circuit condenser coil (e.g., 140), then through thedehumidification wheel (e.g., 130), and then through the recovery wheel(e.g., 110). Further still, in many embodiments, the supply airstream(e.g., 1135) passes through the secondary circuit evaporator coil (e.g.,160). Even further, in some embodiments, the supply airstream passes theoutdoor air first through the recovery wheel (e.g., 110), then throughthe primary cooling coil (e.g., 1150), then through the secondarycircuit evaporator coil (e.g., 160), then through the (e.g.,desiccant-based) dehumidification wheel (e.g., 130), and then to thespace.

In a number of embodiments, the dedicated outdoor air supply (e.g.,system or subsystem 1100) further includes a primary direct-expansionrefrigeration circuit (e.g., 1122), for example, that includes at leastone primary circuit compressor (e.g., 1120), a primary circuitevaporator coil (e.g., 1150), and a primary circuit condenser coil(e.g., 1104). In various embodiments, for example, the supply airstream(e.g., 1135) passes through the primary circuit evaporator coil (e.g.,1150), the primary cooling coil is the primary circuit evaporator coil(e.g., 1150), the at least one condenser coil (e.g., described above) isor includes the primary circuit condenser coil (e.g., 1104), or acombination thereof. In some embodiments, for instance, the exhaustairstream (e.g., 1115) passes the return air (e.g., 1145) from the spacefirst through the dehumidification wheel (e.g., 130), and then throughthe recovery wheel (e.g., 110), and then through the primary circuitcondenser coil (e.g., 1104), for example, as shown. Moreover, in manyembodiments, the primary direct-expansion refrigeration circuit (e.g.,1122) is a heat pump that both cools and heats the primary circuitevaporator coil (e.g., 1104) depending on whether cooling or heating ofthe space is demanded.

In some embodiments, the dedicated outdoor air supply (e.g., subsystem)further includes an evaporative cooler (not shown, e.g. as describedherein), for example, that precools air entering the primary circuitcondenser coil (e.g., 1104). In particular embodiments, for example, theevaporative cooler is located between the recovery wheel (e.g., 110) andthe primary circuit condenser coil (e.g., 1104), the exhaust airstream(e.g., 1115) passes through the evaporative cooler, or both. Further, insome embodiments, supplemental outdoor air (not shown) is added to theexhaust airstream of the dedicated outdoor air supply (e.g., subsystem).In various embodiments, the supplemental outdoor air passes through theevaporative cooler, the supplemental outdoor air passes through theprimary circuit condenser coil (e.g., in some embodiments, after thesupplemental outdoor air passes through the evaporative cooler), orboth. Still further, in a number of embodiments, supplemental outdoorair is added to the exhaust airstream, the supplemental outdoor airpasses through the primary circuit condenser coil (e.g., 1104), thesupplemental outdoor air is added to the exhaust airstream between therecovery wheel and the primary circuit condenser coil, or a combinationthereof.

Turning now from units and systems (e.g., for controlling temperatureand humidity within a space in a building, for instance, airconditioning or HVAC units or systems) to methods, various embodimentsare or include methods, for instance, for controlling temperature andhumidity within a space, for example, in a building. In manyembodiments, such a method includes certain acts, which can be performedin different orders, or in some embodiments, some or all of which areperformed, simultaneously. Methods 1200 and 1300 shown in FIGS. 12 and13 are examples of embodiments. Different embodiments include some orall of the acts shown or described, or a combination of such acts.

Method 1200, for instance, is an example of a method of controllingtemperature and humidity within a space, for example, in a building.Method 1200 includes (e.g., simultaneous) acts of: operating a secondarydirect-expansion refrigeration circuit (e.g., act 1210, for instance,secondary circuit 125 or 325 shown in FIGS. 1, 3, and 11). In someembodiments, for example, this act (e.g., 1210) includes operating(i.e., running) a secondary compressor (e.g., 120 or 320). Further, inthe embodiment illustrated, method 1200 includes passing outdoor air(e.g., act 1220, for example, outdoor air 305 shown in FIG. 3), forexample, through various components, for instance, in a particular order(e.g., to a space). In the embodiment shown, method 1200 also includespassing return air (e.g., act 1230, for example, return air 345 or 1145shown in FIGS. 3 and 11), for example, from the space, for instance,through various (e.g., of the same or different) components, forexample, in a certain order.

In a number of embodiments, for example, the secondary direct-expansionrefrigeration circuit compressor (e.g., 120 or 320) is part of thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325 ofact 1210), for instance, that includes (e.g., in addition to thesecondary direct-expansion refrigeration circuit compressor) a secondarydirect-expansion refrigeration circuit evaporator coil or secondarycooling coil (e.g., 160 or 360), and a secondary direct-expansionrefrigeration circuit condenser coil or heating coil (e.g., 140 or 340).Further, various embodiments include (e.g., in act 1220) passing outdoorair (e.g., outdoor air 305 or supply airstream 335 or 1135) firstthrough a recovery wheel (e.g., 110 or 310), then through a primarycooling coil (e.g., 150, 350, or 1150), then through the secondarydirect-expansion refrigeration circuit evaporator coil or secondarycooling coil (e.g., 160 or 360), then through a (e.g., passive)dehumidification wheel (e.g., 130 or 330), and then to the space. Forexample, in the embodiment shown in FIG. 3, act 1220 can be performedusing supply fan 113, 313, or 1113, for example, under the control ofcontroller 170 shown in FIG.

1.

Still further, a number of embodiments (e.g., of method 1200) include(e.g., in act 1230) passing return air (e.g., 345 or 1145, for instance,with exhaust fan 112, 312, or 1112) from the space or an exhaustairstream (e.g., 315 or 1115) first through the secondarydirect-expansion refrigeration circuit condenser coil, heating coil, orpreheating coil (e.g., 140 or 340), then through the (e.g., passive)dehumidification wheel (e.g., 130 or 330), and then through the recoverywheel (e.g., 110 or 310). In various embodiments, the act of passing thereturn air (e.g., 1230) from the space is performed by operating anexhaust fan (e.g., 112, 312, or 1112) that blows the return air (e.g.,345 or 1145). Further, in various embodiments the act of passing thereturn air (e.g., 1230) from the space includes exhausting the returnair (e.g., 345 or 1145), for example, to outdoors, after the return air(e.g., 345 or 1145) passes through the recovery wheel (e.g., 110 or310). In some embodiments, the exhaust airstream (e.g., 315) isexhausted to or used to ventilate another space, for example, a parkinggarage, attic, or equipment room, as other examples.

Various methods, including method 1200, further include transferringheat or moisture (e.g., in act 1240), or both, for example, betweenairstreams (e.g., supply air to exhaust air when operating in a coolingmode). Some embodiments, for example, specifically include (e.g., in act1240) transferring moisture from the outdoor air (e.g., 305) to thereturn air (e.g., 345 or 1145), for example, with a desiccant coating onthe recovery wheel (e.g., 110 or 310). Further, many embodiments include(e.g., in act 1240) transferring sensible heat from the outdoor air(e.g., 305) to the return air (e.g., 345 or 1145) with the recoverywheel (e.g., 110 or 310).

A number of embodiments further include primary conditioning (e.g., act1250 of method 1200, for instance, operating a primary cooling system,subsystem, or circuit), for example, that cools, or in some embodiments,(e.g., when demanded, for instance, in a heating mode) heats (e.g., atprimary coil 150, 350, or 1150, or at a different coil in seriestherewith), the supply airstream (e.g., 335 or 1135). In someembodiments, for example, act 1250 includes operating at least oneprimary chiller that chills cooling water, passing the cooling waterthrough the primary cooling coil (e.g., 150, 350, or 1150), or both. Onthe other hand, other embodiments include operating a primary directexpansion refrigeration circuit (e.g., 1122 shown in FIG. 11) that coolsthe primary cooling coil (e.g., 1150) and that, in the embodiment shownin FIG. 11, rejects heat through a primary condenser coil (e.g., 1104).Method 1200 is an example of such a method involving a primary directexpansion refrigeration circuit (e.g., 1122) as well, and also includesact 1260 of providing a heat source or sink, for example, to reject orobtain heat that is transferred in act 1250. Certain (e.g., of these)embodiments include, for example, passing (e.g., in act 1230) the returnair (e.g., 1145) from the space first through the secondary circuitcondenser coil (e.g., 140), then through the (e.g., passive)dehumidification wheel (e.g., 130), then through the recovery wheel(e.g., 110, for instance, performing act 1240), and then through theprimary condenser coil (e.g., 1104, performing act 1260).

Further, various methods (e.g., 1200) include controlling humidity(e.g., act 1270), for example, in the space or in the supply air (e.g.,337). In particular embodiments, controlling humidity (e.g., act 1270),or other acts of method 1200 (e.g., act 1210), can include condensingmoisture out of the outdoor air (e.g., 305 or supply airstream 335 or1135) with the secondary circuit evaporator coil (e.g., 160 or 360),transferring sensible heat to the return air with the secondary circuitcondenser coil (e.g., 140 or 340), or both, as examples. Other ways ofcontrolling humidity are described herein, including using the primarycooling coil, recovery wheel, and (e.g., passive) dehumidificationwheel.

Various embodiments involve transferring certain quantities, forexample, of heat or moisture, for instance, from particular sources toparticular destinations. Method 1300 in FIG. 13 illustrates someexamples. Method 1300 include certain acts, many of which can involvetransferring certain quantities. As used herein, a “quantity” can be arate, for example, a quantity (e.g., of energy) per unit of time, whichcan vary depending on conditions, demand, or both. In a number ofembodiments, an act involving a quantity can be steady (e.g., steadystate), but in various embodiments, the rate can vary over time, forexample, as the conditions that require the cooling, dehumidification,etc., change. Such acts can include, for example, transferring (e.g., inact 1310), a first quantity of heat. In some embodiments, for example,the first quantity of heat is transferred (e.g., in act 1310) to anexhaust airstream (e.g., 115 or 315) from outdoor air (e.g., 305)entering a supply airstream (e.g., 335 or 1135). In various embodiments,the first quantity of heat (e.g., of act 1310) can be, or can include,sensible or latent heat, or both. In a number of embodiments, the firstquantity of heat can be transferred, (e.g., in act 1310), for instance,with a recovery wheel (e.g., 110 or 310). FIGS. 3 and 6-9, includingpsychometric chart 800, provide several specific examples of quantities.FIGS. 2, 4, and 5, including psychometric chart 500, provide severalspecific examples of prior art that may be used for comparison, forexample, to illustrate differences or potential improvements.

Various methods (e.g., 1300) further include an act (e.g., 1320) ofconditioning (e.g., cooling when in a cooling mode) the supply airstream(e.g., 335 or 1135), for example, with a primary cooling coil (e.g.,150, 350, or 1150), for example, downstream of the transferring (e.g.,in act 1310) of the first quantity of (e.g., sensible or latent) heat,for instance. In some embodiments, conditioning the supply air (e.g.,act 1320) includes condensing a second quantity of moisture from thesupply airstream (e.g., 335 or 1135). As used herein, when referring toa particular airstream, “downstream” means relative to that airstream.For example, in the act (e.g., 1320) of conditioning the supplyairstream (e.g., 335 or 1135) downstream of the transferring of thefirst quantity of sensible or latent heat, “downstream” means relativeto the supply airstream (e.g., 335 or 1135).

Further, many embodiments (e.g., method 1300) include transferring(e.g., in act 1330) a third quantity of heat from the supply airstream(e.g., 335 or 1135) to return air (e.g., 345 or 1145) entering theexhaust airstream (e.g., 315 or 1115). In some embodiments, this (e.g.,act 1330) is done with a secondary direct-expansion refrigerationcircuit (e.g., 125 or 325), for example. In various embodiments, forexample, the transferring (e.g., act 1330) of the third quantity of heatfrom the supply airstream (e.g., 335 or 1135) takes place in the supplyairstream (e.g., 335 or 1135) downstream of the conditioning or cooling(e.g., act 1320) of the supply airstream (e.g., 335 or 1135, forexample, with the primary cooling coil, for instance, 150, 350, or1150). Still further, in some embodiments, the transferring of the thirdquantity of heat (e.g., in act 1330) from the supply airstream (e.g.,335 or 1135) includes condensing a fourth quantity of moisture from thesupply airstream (e.g., 335 or 1135), for example, at the secondaryevaporator coil (e.g., 160 or 360). Further, in a number of embodiments,more heat is transferred (e.g., in act 1330) to the return air (e.g.,345 or 1145) entering the exhaust airstream (e.g., 315 or 1115), forexample, at the secondary condenser coil (e.g., 140 or 340) than istransferred (e.g., in act 1330) from the supply airstream (e.g., 335 or1135), even if latent energy is considered, due to energy added bysecondary direct-expansion refrigeration circuit (e.g., 125 or 325, forinstance, by compressor 120 or 320). In some embodiments, more than thethird quantity of heat is transferred (e.g., in act 1330) to the returnair (e.g., 345 or 1145) entering the exhaust airstream (e.g., 315 or1115).

In a number of embodiments, such a method (e.g., 1300) can furtherinclude transferring (e.g., in act 1350) a fifth quantity of moisture,for example, from the supply airstream (e.g., 335 or 1135) to theexhaust airstream (e.g., 315 or 1115). In a number of embodiments, forexample, this (e.g., act 1350) can be performed, with a (e.g., desiccantbased, passive, or both) dehumidification wheel (e.g., 130 or 330). Evenfurther, in various embodiments, the transferring (e.g., in act 1350) ofthe fifth quantity of moisture from the supply airstream (e.g., 335 or1135) to the exhaust airstream (e.g., 315 or 1115) takes place in thesupply airstream (e.g., 335 or 1135) downstream of the transferring(e.g., in act 1330) of the third quantity of heat from the supplyairstream (e.g., 335 or 1135), for example, with the secondarydirect-expansion refrigeration circuit) evaporator coil (e.g., 160 or360) to the return air (e.g., 345 or 1145) entering the exhaustairstream (e.g., 315 or 1115). Further still, in various embodiments,the transferring (e.g., in act 1350) of the fifth quantity of moisturefrom the supply airstream (e.g., 335 or 1135) to the exhaust airstream(e.g., 315 or 1115) takes place in the exhaust airstream (e.g., 315 or1115) downstream of the transferring (e.g., in act 1330) of the thirdquantity of heat (e.g., with the secondary direct-expansionrefrigeration circuit condenser coil (e.g., 140 or 340) from the supplyairstream (e.g., 335 or 1135) to the return air (e.g., 345 or 1145)entering the exhaust airstream (e.g., 315 or 1115).

Even further still, in some such embodiments, in conjunction with thetransferring (e.g., in act 1350) of the fifth quantity of moisture fromthe supply airstream (e.g., 335 or 1135) to the exhaust airstream (e.g.,315 or 1115), the method (e.g., 1300) includes transferring (e.g., inact 1360) a sixth quantity of sensible heat from the exhaust airstream(e.g., 315 or 1115) to the supply airstream (e.g., 335 or 1135), forexample, with the (e.g., passive, desiccant-based, or both)dehumidification wheel (e.g., 130 or 330). As used herein, in thiscontext, “in conjunction with” means at the same location or using thesame component (e.g., with the dehumidification wheel (e.g., 130 or330). Moreover, in various such embodiments (e.g., method 1300), the act(e.g., 1360) of transferring of the sixth quantity of sensible heat(e.g., with the dehumidification wheel, for instance, 130 or 330) fromthe exhaust airstream (e.g., 315 or 1115) to the supply airstream (e.g.,335 or 1135) takes place in the supply airstream (e.g., 335 or 1135)downstream of the transferring (e.g., in act 1330) of the third quantityof heat (e.g., with the secondary direct-expansion refrigerationcircuit, for instance, 125 or 325) from the supply airstream (e.g., 335or 1135) to the return air (e.g., 345 or 1145) entering the exhaustairstream (e.g., 315 or 1115). Further, in various embodiments, thetransferring (e.g., in act 1360) of the sixth quantity of sensible heatfrom the exhaust airstream (e.g., 315 or 1115) to the supply airstream(e.g., 335 or 1135) takes place in the exhaust airstream (e.g., 315 or1115) downstream of the transferring (e.g., in act 1330) of the thirdquantity of heat from the supply airstream (e.g., 335 or 1135) to returnair (e.g., 345 or 1145) entering the exhaust airstream (e.g., 315 or1115, for example, with secondary direct-expansion refrigeration circuitcondenser coil 140 or 340).

Still further, various methods (e.g., 1300) include delivering (e.g., inact 1270) the supply airstream (e.g., 335 or 1135) to the space (e.g.,through the supply ductwork) downstream of the transferring (e.g., inact 1260) of the sixth quantity of sensible heat from the exhaustairstream (e.g., 315 or 1115) to the supply airstream (e.g., 335 or1135), for example, with the (e.g., passive) dehumidification wheel(e.g., 130 or 330). In many embodiments, the dehumidification wheel(e.g., 130 or 330) is designed and operated to maximize moisturetransfer (e.g., the fifth quantity of moisture, for instance,transferred in act 1350) and minimize heat transfer (e.g., the sixthquantity of sensible heat, for instance, transferred in act 1360). Invarious embodiments, however, the sixth quantity of sensible heat, whichincludes some of the third quantity of heat (e.g., transferred via thesecondary direct-expansion refrigeration circuit, for example, 125 or325, transferred in act 1330) provides for warmer supply air (e.g.,337), for example, cooled and dehumidified outdoor air (e.g., 305)despite a low supply air (e.g., 337) temperature prior to thetransferring (e.g., in act 1360) of the sixth quantity of sensible heatfrom the exhaust airstream (e.g., 315 or 1115) to the supply airstream(e.g., 335 or 1135, for example, with the dehumidification wheel, forinstance, 130 or 330). This can achieve a low dew point of the supplyair (e.g., 337) delivered to the space (e.g., in act 1390) and also canavoid having supply air (e.g., 337) delivered to the space that isoverly or uncomfortably cold.

Even further, in various embodiments, the transferring (e.g., in act1310) of the first quantity of (e.g., sensible or latent) heat from theoutdoor air (e.g., 305) entering the supply airstream (e.g., 335 or1135) to the exhaust airstream (e.g., 315 or 1115, for instance, withthe recovery wheel, for example, 110 or 310) takes place in the exhaustairstream (e.g., 315 or 1115) downstream of the transferring (e.g., inact 1350) of the fifth quantity of moisture from the supply airstream(e.g., 335 or 1135) to the exhaust airstream (e.g., 315 or 1115, forinstance, with the (e.g., passive) dehumidification wheel, for example,130 or 330). Further, in some embodiments, the act (e.g., 1310) oftransferring the first quantity of heat from outdoor air (e.g., 305)entering the supply airstream (e.g., 335 or 1135) to the exhaustairstream (e.g., 315 or 1115) further includes transferring a seventhquantity of moisture from the outdoor air (e.g., 305) entering thesupply airstream (e.g., 335 or 1135) to the exhaust airstream (e.g., 315or 1115), for example, downstream, relative to the exhaust airstream, ofthe transferring (e.g., in act 1350) of the fifth quantity of moisturefrom the supply airstream (e.g., 335 or 1135) to the exhaust airstream(e.g., 315 or 1115). The seventh quantity of moisture is transferred(e.g., in act 1310), in many embodiments, with a desiccant coating onthe total energy recovery wheel (e.g., 110 or 310), for example, inconjunction with transferring sensible heat. In various embodiments, theseventh quantity of moisture is transferred (e.g., in act 1310) from theoutdoor air (e.g., 305) entering the supply airstream (e.g., 335 or1135) to the exhaust airstream (e.g., 315 or 1115), downstream (withrespect to the exhaust airstream) of the dehumidification wheel (e.g.,130 or 330).

Moreover, in some embodiments, or under some conditions, theconditioning (e.g., cooling) of the supply airstream (e.g., 1135 shownin FIG. 11, for instance, in act 1320), for example, downstream of thetransferring (e.g., in act 1310) of the first quantity of heat includesremoving an eighth quantity of heat from the supply airstream (e.g., atprimary cooling coil 1150) and rejecting (e.g., in act 1328) the eighthquantity of heat, for instance, to the exhaust airstream (e.g., 1115),for example, downstream (i.e., relative to the exhaust airstream) of thetransferring (e.g., in act 1310) of the first quantity of heat to theexhaust airstream (e.g., at primary condenser coil 1104 shown in FIG.11). In various embodiments, the conditioning or cooling (e.g., in act1320) of the supply airstream (e.g., downstream, relative to the supplyairstream, of the transferring of the first quantity of heat, forexample, in act 1310) takes place at the primary cooling coil (e.g.,1150), for example.

In various embodiments, further heat (e.g., compressor energy, forinstance, from compressor 1120, that has been converted to heat by firststage or primary direct expansion refrigeration circuit 1122), inaddition to the eighth quantity of heat that was removed from the supplyairstream (e.g., 1135), is rejected (e.g., in act 1328) to the exhaustairstream (e.g., 1115), for example, downstream (i.e., relative to theexhaust airstream) of the transferring (e.g., in act 1310) of the firstquantity of heat to the exhaust airstream. Further, in a number ofembodiments, including in the embodiment illustrated, the conditioning(e.g., cooling, for example, in act 1320) of the supply airstream (e.g.,1135) downstream of the transferring (e.g., in act 1310) of the firstquantity of heat includes operating a primary direct-expansionrefrigeration circuit (e.g., 1122) that includes at least one primarycircuit compressor (e.g., 1120), a primary circuit evaporator coil(e.g., 1150) located in the supply airstream (e.g., 1135), and a primarycircuit condenser coil (e.g., 1104). In a number of embodiments, theprimary circuit condenser coil (e.g., 1104) is located in the exhaustairstream (e.g., 1115), for example, downstream (i.e., relative to theexhaust airstream) of the recovery wheel (e.g., 110) where the firstquantity of heat is transferred (e.g., in act 1310) to the exhaustairstream (e.g., 1115).

Further, various embodiments include separating the outdoor air (e.g.,305 shown in FIG. 3) or supply airstream (e.g., 335 or 1135) from thereturn air (e.g., 345 or 1145) or exhaust airstream (e.g., 315 or 1115),for example, with a partition (e.g., 111 or 311). In variousembodiments, for instance, the recovery wheel (e.g., 110 or 310) islocated in a first opening (e.g., 601 shown in FIG. 6) in the partition(e.g., 111 or 311), the (e.g., passive) dehumidification wheel (e.g.,130 or 330) is located in a second opening (e.g., 602 shown in FIG. 6)in the partition (e.g., 111 or 311), or both. Still further, variousmethods include guiding (e.g., with ductwork or walls) the outdoor air(e.g., 305) and the return air (e.g., 345 or 1145), for example, insubstantially opposite directions (e.g., as shown). Even further, anumber of embodiments include (e.g., an act of) enclosing within anenclosure (e.g., 101), the recovery wheel (e.g., 110 or 310), thedehumidification wheel (e.g., 130 or 330), the primary cooling coil(e.g., 150, 350, or 1150), the secondary direct-expansion refrigerationcircuit evaporator coil (e.g., 160 or 360), the secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or340), or a combination thereof. In some embodiments, for example, thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325) issubstantially or entirely enclosed with the enclosure, for example.Further still, various embodiments include enclosing within theenclosure the supply fan (e.g., 113, 313, or 1113) that moves theoutdoor air (e.g., 305) or supply airstream (e.g., 335 or 1135), forexample, first through the recovery wheel (e.g., 110 or 310), thenthrough the primary cooling coil (e.g., 150, 350, or 1150), then throughthe secondary cooling coil or secondary direct-expansion refrigerationcircuit evaporator coil (e.g., 160 or 360), then through thedehumidification wheel (e.g., 130 or 330), and then to the space (e.g.,in act 1390). Even further still, various embodiments include (e.g., anact of) enclosing within the enclosure (e.g., 101) the exhaust fan(e.g., 112, 312, or 1112) that moves the return air (e.g., 345 or 1145)(e.g., from the space), for instance, first through the heating coil orsecondary direct-expansion refrigeration circuit condenser coil (e.g.,140 or 340), then through the dehumidification wheel (e.g., 130 or 330),and then through the recovery wheel (e.g., 110 or 310). Moreover, someembodiments include (e.g., an act of) enclosing within the enclosure(e.g., 101) the partition (e.g., 111 or 311) that separates the outdoorair (e.g., 305) or supply airstream (e.g., 335 or 1135) from the returnair (e.g., 345 or 1145), for example, within the enclosure.

In many embodiments, the method includes (or act 1390 includes, forexample) passing the supply air (e.g., 337), supply airstream (e.g., 335or 1135), or outdoor air (e.g., 305, for example, once cooled anddehumidified, as described herein) through supply ductwork that deliversthe outdoor air (e.g., 305) or supply airstream (e.g., 335 or 1135) tothe space, for example, after the outdoor air (e.g., 305) or supplyairstream (e.g., 335 or 1135) passes through the (e.g., passive)dehumidification wheel (e.g., 130 or 330). Further, in some embodiments,the method (or act 1390) includes delivering the outdoor air (e.g., 305)or supply airstream (e.g., 335 or 1135) to multiple zones within thespace, cooling the space, for example, with multiple chilled beamslocated within the space, or both. Still further, some embodimentsinclude operating a main chiller that chills cooling water, or chillingthe cooling water, and passing the cooling water through the multiplechilled beams located within the space. Even further, in someembodiments, the method includes (or act 1250 or 1320 includes) passingthe cooling water from the main chiller (e.g., the primary chiller, or,in some embodiments, from a separate chiller) through the primarycooling coil (e.g., 150 or 350). Further still, in particularembodiments, the act of cooling the space (e.g., with multiple chilledbeams located within the space) or act 1390, as another example,includes cooling the space with active chilled beams, delivering theoutdoor air or supply air (e.g., 337) to the multiple chilled beamslocated within the space, inducing room air across the chilled beams orcooling coils within the chilled beams so as to enhance the coolingcapacity delivered to the space, or a combination thereof. For example,in certain embodiments, the act of cooling the space with the multiplechilled beams located within the space, or act 1390 of delivering thesupply air, includes moving the supply airstream (e.g., 335 or 1135)delivered to the space through slots or nozzles within the multiplechilled beams to induce room air in the space over coils within themultiple chilled beams to enhance cooling capacity provided by themultiple chilled beams.

Even further still, in certain embodiments, act 1390, or, in particularembodiments, the act of cooling the space with the multiple chilledbeams located within the space, includes cooling each of the multiplezones with at least one of the multiple chilled beams, circulatingchilled water through at least one of the multiple chilled beams, forexample, with a separate chilled water zone pump for each of themultiple zones, measuring temperature of chilled water that passesthrough the multiple chilled beams located within the space, modulatinga chilled water control valve for each of the multiple zones, passingchilled water from a chilled water supply header into the at least oneof the multiple chilled beams that are located within that zone, or acombination thereof. Moreover, in some embodiments, the method includescontrolling flow of chilled water from a chilled water supply headerinto the (e.g., multiple) chilled beams to avoid formation ofcondensation on the multiple chilled beams, using a digital controllerfor each of the multiple zones to control the flow of the chilled waterfrom the chilled water supply header into the at least one of themultiple chilled beams in that zone, controlling zone air temperature inresponse to a measurement of zone air temperature, or a combinationthereof, as examples. Other alternatives and other embodiments aredescribed herein or would be apparent to a person of ordinary skill inthe art. For example, other alternatives for cooling the space or zonesare also described herein and acts of cooling the space with otherequipment (e.g., as described herein) besides chilled beams are includedin other embodiments.

Various methods or acts, in particular embodiments, include rejectingheat (e.g., from the space) to a geothermal heat sink (e.g., in act 1260shown in FIG. 12. For example, some embodiments include rejecting heat(e.g., obtained in act 1250 or 1320) from the primary cooling coil(e.g., 150, 350, or 1150) to the geothermal heat sink. Further, certainembodiments include using a direct-expansion refrigeration circuit thatuses the geothermal heat sink as a geothermal condenser in a coolingmode. Still further, in some (e.g., heat pump) embodiments, the methodincludes using the geothermal heat sink as an evaporator in a heatingmode. Further still, in some embodiments, the method includes operatinga primary direct-expansion refrigeration circuit that uses the primarycooling coil (e.g., 150, 350, or 1150) as a primary evaporator (e.g., inact 1250 or 1320). Even further, in some embodiments, the method (e.g.,1200 or 1300) includes operating a heat pump that both cools and heatsthe primary cooling coil (e.g., 150, 350, or 1150) depending on whethercooling or heating of the space is demanded, for example, by at leastone thermostat located within the space.

Even further still, in various embodiments, the space includes multiplezones, and the method includes cooling each of the multiple zones withat least one zone direct-expansion refrigeration circuit, for example,by operating a zone compressor, cooling a zone indoor air coil, andrejecting heat from the zone through a zone (e.g., outdoor) heatexchanger, for example. In various embodiments, the act of cooling eachof the multiple zones with at least one zone direct-expansionrefrigeration circuit includes rejecting heat from the zone to ageothermal heat exchanger (e.g., the zone outdoor heat exchanger).Further, in various embodiments, for instance, each at least one zonedirect-expansion refrigeration circuits is a heat pump and the methodfurther includes heating each of the multiple zones with the at leastone zone direct-expansion refrigeration circuit by operating the zonecompressor, heating the zone indoor air coil, and obtaining heat for thezone (e.g., in act 1260) through the zone outdoor heat exchanger (e.g.,geothermal heat exchanger), for example.

In some embodiments, the method includes transferring more heat with theprimary cooling coil (e.g., 150, 350, or 1150, for instance, in act 1250or 1320), for example, at maximum capacity, than the secondary coolingcoil or secondary direct-expansion refrigeration circuit evaporator coil(e.g., 160 or 360, for instance, in act 1210 or 1330), for instance, atmaximum capacity. For example, in particular embodiments, the methodincludes transferring more than twice as much heat with the primarycooling coil (e.g., 150, 350, or 1150) at maximum capacity than thesecondary cooling coil or secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) evaporator coil (e.g., 160 or 360) transfersat maximum capacity. Further, in some embodiments, the method includespassing (e.g., in act 1220) the outdoor air (e.g., 305) or supplyairstream (e.g., 335 or 1135) at a greater volumetric flowrate than thereturn air (e.g., 345 or 1145, for instance, in act 1230), for example,to pressurize the building. Further still, in some embodiments, themethod includes modulating the speed of the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) or compressor (e.g., 120 or320, for example, in act 1210, 1270, or 1330), for instance, to controlthe humidity of the air delivered to the space (e.g., in act 1390).

Even further, in some embodiments, the method includes operating (e.g.,in act 1210 or 1330) the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325), or specifically, the compressor (e.g., 120or 320), for example, whenever the system (e.g., 100, 300, or 1100) isoperating (e.g., in act 1250 or 1320) in a cooling mode. Still further,in particular embodiments, the method includes modulating cooling at theprimary cooling coil (e.g., 150, 350, or 1150, for instance, in act 1250or 1320), for example, to control temperature of the space whenoperating in a cooling mode, when operating in a dehumidification mode(e.g., in act 1270), or both. Even further still, in some embodiments,the method includes modulating cooling at the primary cooling coil(e.g., 150, 350, or 1150) to control temperature of the (e.g., airconditioned) outdoor air (e.g., 305) or supply airstream (e.g., 335,1135) leaving the (e.g., passive) dehumidification wheel (e.g., 130 or330, for example, supply air 337) when operating in a cooling mode, whenoperating in a dehumidification mode, or both. Moreover, in certainembodiments, the method includes modulating (e.g., in act 1210 or 1330)the speed of the secondary direct-expansion refrigeration circuit (e.g.,125 or 325) compressor (e.g., 120 or 320) to adjust reheat capacity atthe secondary condenser coil (e.g., 140 or 340) when operating in acooling mode, when operating in a dehumidification mode (e.g., in act1270), or both.

In some embodiments, the method further includes operating in aneconomizer mode in which cooling at the primary cooling coil (e.g., 150,350, or 1150, for example, act 1250 or 1320) is turned off and thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325) andcompressor (e.g., 120 or 320) is operated (e.g., in act 1210 or 1330),for example, to dehumidify (e.g., in act 1270) the outdoor air (e.g.,305) or supply airstream (e.g., 335 or 1135) with the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) orspecifically the evaporator coil (e.g., 160 or 360) and, in a number ofembodiments, with the dehumidification wheel (e.g., 130 or 330).Further, in various embodiments, the method includes transferringmoisture (e.g., in act 1240, 1270, or 1310) from the outdoor air (e.g.,305) or supply airstream (e.g., 315 or 1115) to the return air (e.g.,345 or 1145) or exhaust airstream (e.g., 315 or 1115) with the (e.g.,total energy) recovery wheel (e.g., 110 or 310).

Still further, in some embodiments, the method includes heating theoutdoor air (e.g., 305) or supply airstream (e.g., 335 or 1135) whenoperating in a heating mode using a heating coil (e.g., within theenclosure, for instance, 101) that is separate from the primary coil(e.g., 150, 350, or 1150) and that is separate from the secondarycooling coil or secondary direct-expansion refrigeration circuitevaporator coil (e.g., 160 or 360). In some embodiments, however, themethod includes heating the outdoor air (e.g., 305) or supply airstream(e.g., 335 or 1135) when operating in the heating mode (e.g., in act1250 or 1320) using the primary coil (e.g., 150, 350, or 1150) orprimary direct expansion circuit (e.g., 1122). Even further, in someembodiments, the method (e.g., 1200 or 1300) includes transferringmoisture (e.g., in act 1240, 1270, or 1350) from the outdoor air (e.g.,305) or supply airstream (e.g., 335 or 1135) to the return air (e.g.,345 or 1145) or the exhaust airstream (e.g., 315 or 1115) with thedehumidification wheel (e.g., 130 or 330). Further still, in particularembodiments, the method includes transferring sensible heat (e.g., inact 1360) from the return air (e.g., 345 or 1145) or exhaust airstream(e.g., 315 or 1115) to the outdoor air (e.g., 305) or supply airstream(e.g., 335 or 1135) with the dehumidification wheel (e.g., 130 330).

Even further still, in various embodiments, the method (e.g., 1200 or1300) includes condensing moisture out of the outdoor air (e.g., 305) orsupply airstream (e.g., 335 or 1135) with the primary cooling coil(e.g., 150, 350, or 1150, for example, in act 1220, 1250, 1270, or1320), condensing (e.g., additional) moisture out of the outdoor air(e.g., 305) or supply airstream (e.g., 335 or 1135) with the secondarycooling coil or secondary direct-expansion refrigeration circuitevaporator coil (e.g., 160 or 360, for instance, in act 1210, 1220,1270, or 1330), transferring sensible heat to the return air (e.g., 345or 1145) with the heating coil or secondary direct-expansionrefrigeration circuit condenser coil (e.g., 140 or 340, for example, inact 1210, 1230, or 1330), or a combination thereof. Moreover, in certainembodiments, the method includes transferring heat from the secondarycooling coil or secondary direct-expansion refrigeration circuitevaporator coil (e.g., 160 or 360) to the heating coil or secondarydirect-expansion refrigeration circuit condenser coil (e.g., 140 or 340)with the secondary direct-expansion refrigeration circuit (compressor(e.g., 120 or 320), the secondary direct-expansion refrigeration circuit(e.g., 125 or 325), or both (e.g., in act 1210, 1220, 1230, 1330, or acombination thereof).

In some embodiments, the method or act (e.g., 1210, 1270, or 1330) ofoperating the secondary compressor (e.g., 120 or 320) includes ensuringthat condensation does not occur during low airflow conditions on thereturn air (e.g., 345 or 1145) or exhaust airstream (e.g., 315 or 1115)side, for example, on the partition (e.g., 111 or 311) described above,for instance, resulting from pressurization needs or variable volumeoperation. Certain embodiments include, for example, increasing thetemperature entering or leaving (or both) the return air (e.g., 345 or1145) side of the dehumidification wheel (e.g., 130 or 330), forinstance, to avoid condensation, for example, during low airflowconditions, for instance, on the return air (e.g., 345 or 1145) side,for instance, on the partition (e.g., 111 or 311), for example,resulting from pressurization needs or variable volume operation.

Further still, in some embodiments, the method or act (e.g., 1210 or1330 of operating the secondary compressor (e.g., 120 or 320) or thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325)includes providing cooling when the chilled water plant or chiller isturned off, for example, due to temperature lockout or time of year, asexamples. Even further, certain embodiments include, for example,operating the system (e.g., 100 or 300) in a part-load mode in whichcooling at the primary cooling coil (e.g., 150, 350, or 1150) is turnedoff and the supply airstream (e.g., 335 or 1135) is cooled using thesecondary cooling coil (e.g., 160 or 360). Particular embodimentsspecifically include (e.g., in act 1210 or 1330) modulating cooling atthe secondary cooling coil (e.g., 160 or 360), for example, to controltemperature of the supply airstream (e.g., 335 or 1135), the space, orboth.

Some embodiments include (e.g., when warranted by conditions)dehumidifying (e.g., in act 1270) the supply airstream (e.g., 335 or1135), for example, with the secondary cooling coil (e.g., 160 or 360),the (e.g., desiccant-based or passive) dehumidification wheel (e.g., 130or 330, for instance, in act 1240 or 1350), or both (e.g., in additionto or instead of cooling with the secondary cooling coil (e.g., 160 or360), for example, when the primary cooling coil (e.g., 150, 350, or1150, for example, operated in act 1250 or 1320) is turned off. Further,in certain embodiments, the method or act (e.g., 1240, 1270, 1350, 1360,or a combination thereof) includes slowing or stopping thedehumidification wheel (e.g., 130 or 330), for instance, when warrantedby conditions, for example, to reduce or avoid reheating the supplyairstream (e.g., 335 or 1135) after being cooled by the secondarycooling coil (e.g., 160 or 360), for example, when the primary coolingcoil (e.g., 150, 350, or 1150) is turned off). Further still, inparticular embodiments, the method or act (e.g., 1210 or 1330) ofoperating the secondary direct-expansion refrigeration circuit (e.g.,125 or 325) or another act, includes reducing the speed of or stoppingthe recovery wheel (e.g., 110 or 310), for example, when warranted byconditions, for instance, to reduce or avoid heating the supplyairstream (e.g., 335 or 1135), for example, prior to being cooled by thesecondary cooling coil (e.g., 160 or 360), for example, when the primarycooling coil (e.g., 150, 350, or 1150) is turned off.

Even further, in some embodiments, the method or act (e.g., 1210 or1330), for example, of operating the secondary compressor or thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325),includes delivering (e.g., in act 1390) colder air than would bepossible with a chilled water system alone, for instance, due to thetemperature limitation of the chilled water available. In particularembodiments, for example, the method or act includes allowing air thatis colder or that has a lower dew point (or both) to be produced anddelivered (e.g., in act 1390), for example, in conjunction with thedehumidification wheel (e.g., 130 or 330), for instance, in comparisonwith a system (e.g., shown in FIGS. 2 and 4) having chilled water thatdoes not have a secondary direct expansion circuit.

Moreover, in some embodiments, the method or act (e.g., 1210 or 1330),for example, of operating the secondary compressor (e.g., 120 or 320) orthe secondary direct-expansion refrigeration circuit (e.g., 125 or 325),includes operating or modulating (or both) the secondarydirect-expansion refrigeration circuit or compressor (e.g., 120 or 320),for example, the system controller (e.g., 170), to deliver (e.g., in act1390) a warmer supply air (e.g., 337) temperature to the occupied spaceor active chilled beams, for instance, to avoid over-cooling of thespace (e.g., in act 1250 or 1320) by the primary airflow alone, forexample, when low dew point is desired (e.g., in act 1270). For example,in some embodiments, the method or act, for example, of operating thesecondary compressor (e.g., 120 or 320) or the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325), includesoperating or modulating (or both) the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) or compressor (e.g., 120 or320), for example, with the system controller (e.g., 170) to increasesupply air (e.g., 337) temperature delivered (e.g., in act 1390) to theoccupied space or active chilled beams, for instance, in response tospace temperature relative to a thermostat temperature setpoint, or inresponse to supply air (e.g., delivered in act 1390) temperature, forexample, to avoid over-cooling of the space by the primary airflow, forinstance, when low dew point is desired.

In some embodiments, the method or act (e.g., 1210 or 1330), forexample, of operating the secondary compressor (e.g., 120 or 320) or thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325),includes providing cooling, dehumidification (e.g., in act 1270), orcondensation control, for instance, during the startup and constructionphase of a building. For example, in certain embodiments, the method oract (e.g., 1210 or 1330) includes operating, controlling, or modulating(e.g., or a combination thereof) the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) to provide cooling,dehumidification, condensation control, or a combination thereof duringthe startup and construction phase of a building. In some embodiments,due to unconditioned areas, lack of finalized air balancing or controls,the secondary direct-expansion refrigeration circuit (e.g., 125 or 325)can provide temporary cooling (e.g., in act 1210 or 1330), for instance,during times when the space humidity is high or even uncontrollable, atleast to design levels. During these times, for instance, the method oract can prevent condensation, for example, on the dehumidification wheel(e.g., 130 or 330) served by a chilled water system. In varioussituations, this can prevent problems which can damage the wheel orcause corrosion, among other things.

In a number of embodiments, the method or act can include (e.g.,operating or modulating the secondary direct-expansion refrigerationcircuit (e.g., 125 or 325) specifically for (e.g., in act 1210, 1270, or1330) reducing the relative humidity or raising the temperature of thereturn air (e.g., 345 or 1145) or exhaust airstream (e.g., 315 or 1115)before the (e.g., passive) dehumidification wheel (e.g., 130 or 330). Insome embodiments, the method or act can include, for another example,providing temporary cooling, for instance, during times when the spacehumidity is high or even uncontrollable, at least to design levels. Insome embodiments, the method or act can include (e.g., in act 1270), foryet another example, preventing condensation, preventing corrosion,preventing damage, or a combination thereof, for instance, on thedehumidification wheel (e.g., 130 or 330), for example, on systemsserved by a chilled water system.

In various embodiments, the method or act (e.g., 1210 or 1330), forexample, of operating the secondary compressor (e.g., 120 or 320) or thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325),includes modulating down (e.g., reducing in speed or capacity) thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325) orsecondary compressor (e.g., 120 or 320), or even turning off thesecondary direct-expansion refrigeration circuit or secondarycompressor, when conditions within the space have a high sensible loadand a low latent load, when cold air is desired from the system or unit,when condensation on the return air (e.g., 345 or 1145) side leaving the(e.g., passive) dehumidification wheel (e.g., 130 or 330) is not aconcern, or a combination thereof (e.g., all thereof) for example. Undersuch conditions, in some embodiments, the method (e.g., 1200 or 1300)includes cooling (e.g., in act 1210 or 1330) the supply airstream (e.g.,335 or 1135) with the primary cooling coil (e.g., 150, 350, or 1150),for instance. Under such conditions, in certain embodiments, the methodincludes providing dehumidification (e.g., in act 1250, 1270, or 1320)with the primary cooling coil (e.g., 150, 350, or 1150). In someembodiments, for example, the method or act includes turning off thesecondary direct-expansion refrigeration circuit (e.g., 125 or 325) orcompressor (e.g., 120 or 320), for example, that are operated in act1210 or 1330, and providing cooling (e.g., in act 1220, 1250, or 1320)with the primary cooling coil (e.g., 150, 350, or 1150), for example,when conditions within the space have a high sensible load and lowlatent load, when cold air is desired from the unit, when condensationon the return air side (e.g., the exhaust airstream 315 or 1115) leavingthe dehumidification wheel (e.g., 130 or 330) is not a concern, or acombination thereof.

In particular embodiments, the method or act (e.g., 1210 or 1330)includes reducing the speed or capacity of the secondary compressor(e.g., 120 or 320) or reducing the capacity of the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) whenconditions within the space have a high sensible load and low latentload, when cold air is desired from the unit, when condensation on thereturn air side (e.g., the exhaust airstream 315 or 1115) leaving thedehumidification wheel (e.g., 130 or 330) is not a concern, or acombination thereof. In particular embodiments, the method or actincludes implementing these control strategies, for example, underconditions that are relatively hot and dry. In a number of embodiments,the method or act (e.g., 1210, 1270, or 1330) includes modulating downor turning off the secondary direct-expansion refrigeration circuit(e.g., 125 or 325) or compressor (e.g., 120 or 320), for example, inresponse to space temperature relative to one or more thermostatsetpoints and one or more humidity or dew point measurements, forexample.

In some embodiments, the method or act, for example, of operating thesecondary circuit compressor (e.g., 120 or 320) or the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325), includesmaintaining space humidity (e.g., act 1270) for example, duringunoccupied hours, for instance, in a school. In various embodiments, themethod or act (e.g., 1210 or 1330), for example, of operating thesecondary compressor (e.g., 120 or 320) or the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325), includesproviding an unoccupied mode where minimal outdoor air (e.g., 305), andthereby cooling load, is required. In a number of embodiments, themethod or act (e.g., 1210 or 1330), for instance, of operating thesecondary compressor (e.g., 120 or 320) or the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325), includesoperating the secondary direct-expansion refrigeration circuit (e.g.,125 or 325) to perform dehumidification, (e.g., act 1270, for instance,all of the dehumidification needs of the system (e.g., 100, 300, or1100) without operating the primary cooling coil (e.g., 150, 350, or1150), for example, not operating the (or each) chiller or chilledwater, direct expansion (e.g., 1122), or heat pump circuit.

In some embodiments, for example, the method or act includes operatingor modulating the secondary direct-expansion refrigeration circuit(e.g., 125 or 325) or compressor (e.g., 120 or 320) to maintain spacehumidity during unoccupied hours, to provide an unoccupied mode whereminimal outdoor air (e.g., 305), and thereby cooling load, is required,or both. In various embodiments, the method or act (e.g., 1210 or 1330),for example, includes operating or modulating the secondarydirect-expansion refrigeration circuit (e.g., 125 or 325) or compressor(e.g., 120 or 320), for instance, during unoccupied periods, underappropriate conditions, or both, to perform dehumidification (e.g., inact 1270), for example, all of the dehumidification needs, for instance,without operating (e.g., while turning off and leaving turned off) theprimary cooling coil (e.g., 150, 350, or 1150) or the chilled water,direct expansion (e.g., 1122), or heat pump circuit.

Some embodiments include evaporative cooling, supplemental outdoor air,or both. An example of a way of increasing condensing side capacity(e.g., under extreme conditions) is to “flash evaporate” a fine watermist ahead (i.e., upstream) of the condenser coil (e.g., betweenrecovery wheel 110 and condenser coil 1104 in FIG. 11). This cansubstantially lower the air temperature entering the coil, therebyincreasing condensing capacity. Another way to increase condensingcapacity is to use evaporative cooling pads (e.g., 1480 shown in FIGS.14 and 15) in place of the flash evaporation mist (e.g., betweenrecovery wheel 110 and condenser coil 1104). As used herein, flashevaporation of a fine water mist, and evaporative cooler pads, are bothexamples of evaporative cooling (e.g., illustrated by evaporative cooler1480), and are examples of embodiments.

Yet another way to increase condensing capacity is to add outdoor air(e.g., to the exhaust air), for example, upstream of the condensing coil(e.g., between recovery wheel 110 and condenser coil 1104) to increasecondenser airflow. In some embodiments, such added outdoor air is cooledwith evaporative cooling (e.g., in different embodiments, before orafter being combined with return air). An example is shown in FIG. 14.In this embodiment, supplemental outdoor air 1425 is added viasupplemental outdoor air duct 1411, for instance, that extends outdoors(e.g., to a hood). Some embodiments that have supplemental outdoor air(e.g., 1425) include a supplemental outdoor air fan (e.g., 1414, forinstance, a variable-speed fan) that delivers the outdoor air (e.g.,1425). In other embodiments, a supplemental outdoor air fan (e.g., 1414)is not used and supplemental outdoor air (e.g., 1425) is drawn into theexhaust airstream (e.g., 1115), for example, by exhaust air fan 1112,for instance, through a control damper (e.g., 1413). Some embodimentsinclude a supplemental outdoor air fan (e.g., 1414), some embodimentsinclude a supplemental outdoor air control damper (e.g., 1413), and someembodiments include both.

Also shown in FIG. 14, another embodiment, besides outdoor air duct1411, is to include control damper 1412, for example, in partition 111,which is shown opposite air duct 1411. In such embodiments, controldamper 1412 opens to allow part of the supply airstream (e.g., 1135) tobe drawn into the exhaust airstream (e.g., 1115) as supplemental outdoorair, for example, by exhaust air fan 1112. Some embodiments have justone of outdoor air duct 1411 or control damper 1412, some embodimentshave both, and some embodiments have neither. In certain embodiments, anadvantage of control damper 1412 in partition 111 is that air duct 1411may not be required.

Further, some embodiments that include supplemental outdoor air (e.g.,1425) also include an evaporative cooler (e.g., 1480). Otherembodiments, however, that include supplemental outdoor air (e.g.,1425), may omit an evaporative cooler such as evaporative cooler 1480shown in FIG. 14, or may omit evaporative cooling. Further still, someembodiments that include evaporative cooling (e.g., evaporative cooler1480) do not include supplemental outdoor air (e.g., 1425). Evenfurther, in some embodiments that include evaporative cooling (e.g.,evaporative cooler 1480) for cooling condenser air (e.g., for condenser1104), the evaporative cooling is used even when outdoor temperaturesare not extreme, but when cooling is demanded, to reduce electricityconsumption (e.g., by compressor 1120 shown in FIG. 11), to increasecapacity of the direct expansion refrigeration circuit (e.g., 1122), orboth. In certain embodiments, however, evaporative cooling (e.g., withevaporative cooler 1480) is, or can be, turned off (e.g., by the systemcontroller, for example, 170) when humidity or dew point (e.g., ofoutdoor air, return air, or both) exceeds a (e.g., set) threshold.

FIG. 15 illustrates another embodiment with evaporative cooling,supplemental outdoor air, or both. In this embodiment, supplementaloutdoor air 1425 has a separate evaporative cooler 1580 from theevaporative cooler 1480 that precools return air delivered to condenser1104. In this embodiment, if return air 1115 is usually cooler or lesshumid (or both) than supplemental outdoor air 1425, then (e.g., primarycircuit) refrigerant may pass first through condenser 1504 and thenthrough condenser 1104. Other embodiments may omit evaporative cooler1480. Further, other embodiments may omit condenser 1504, but in suchembodiments, supplemental air, if provided, typically passes throughcondenser 1104 (e.g., as shown in

FIG. 14), whether or not the supplemental outdoor air is cooled by anevaporative cooler (e.g., 1480 or 1580).

In various embodiments, a unit or system (e.g., for controllingtemperature and humidity within a space in a building) includes anevaporative cooler (e.g., 1480), for example, that precools air enteringthe primary circuit condenser coil (e.g., 1104 shown in FIG. 11, 14, or15). In particular embodiments, for instance, the evaporative cooler(e.g., 1480) is located between the recovery wheel (e.g., 110) and theprimary circuit condenser coil (e.g., 1104). Still further, in a numberof embodiments, the exhaust airstream (e.g., 1115) passes through theevaporative cooler (e.g., 1480). Even further, in some embodiments,supplemental outdoor air (e.g., 1425) is added to the exhaust airstream(e.g., 1115). In particular embodiments, for example, the supplementaloutdoor air (e.g., 1425) passes through the evaporative cooler (e.g.,1480 shown in FIG. 14 or 1580 shown in FIG. 15). Still further, incertain embodiments, the supplemental outdoor air (e.g., 1425) passesthrough the primary circuit condenser coil (e.g., 1104 shown in FIG. 14or 1504 shown in FIG. 15), for instance, after the supplemental outdoorair (e.g., 1425) passes through the evaporative cooler (e.g., 1480 shownin FIG. 14 or 1580 shown in FIG. 15). Even further still, in someembodiments, the supplemental outdoor air (e.g., 1425) is added to theexhaust airstream (e.g., 1115) between the recovery wheel (e.g., 110)and the primary circuit condenser coil (e.g., 1104, for example, asshown in FIG. 14).

Various embodiments are or include methods, for instance, forcontrolling temperature and humidity within a space, for example, in abuilding. In many embodiments, such a method includes certain acts,which can be performed in different orders, or in some embodiments, someor all of which are performed, simultaneously. Methods 1200 and 1300shown in FIGS. 12 and 13 are examples of embodiments. Differentembodiments include some or all of the acts shown or described, or acombination of such acts. Further, some methods, including variousmethods described herein, including methods 1200 and 1300, can include,in certain embodiments, an act of precooling air (e.g., with anevaporative cooler) before the air (e.g., exhaust air, supplementaloutdoor air, or both) passes through a condenser coil (e.g., for aprimary circuit). Still further, some methods include an act of addingsupplemental outdoor air (e.g., to exhaust air), passing supplementaloutdoor air through a condenser coil (e.g., for a primary circuit), orboth.

As mentioned, certain embodiments provide variable refrigerant flow(VRF), include or are used as a dedicated outdoor air supply (e.g.,subsystem) or dedicated outdoor air system (DOAS), or both. In variousembodiments, two effective ways of increasing the heating capacityavailable to the conditioned spaces are to minimize the heating capacityrequired by the DOAS to condition the outdoor air and to allocate asizeable and more effective “outdoor coil” for the VRF system where asubstantial airflow can be used as a heat source (e.g., cooled to obtainheat to add to the space). Some embodiments (e.g., system 1100) canprovide both of these enhancements.

FIG. 16 illustrates an example of an embodiment that includes a VariableRefrigerant Flow (VRF) system. In FIG. 16, VRF system 1600 feeds threezones, each with a fan coil unit (e.g., 1601, 1602, and 1603). Thesezones are also fed by a DOAS (e.g., 300, 1100, 1400, or others, forinstance, as described herein), in the embodiment shown. In FIG. 16,each of the lines from VRF system 1600 to each of the zones represents asupply refrigerant line and a return refrigerant line. Further, in FIG.16, each of the lines from DOAS 1100 to each of the zones represents asupply air duct and a return air duct. In some embodiments, refrigerantlines or air ducts may branch off from a main line or duct. Furtherstill, in this example, each of the fan coil units (e.g., 1601, 1602,and 1603) includes a fan and an indoor air coil. Various embodimentsalso include an air filter, an enclosure, a thermostat, controls, or acombination thereof, for example.

Various embodiments (e.g., of a system for controlling temperature andhumidity within a space in a building, for instance, as describedherein) include a variable refrigerant flow subsystem (e.g., 1600), forexample, serving multiple zones (e.g., zones 1, 2, and 3 shown in FIG.16) within the space. In a number of embodiments, for example, each ofthe multiple zones includes a fan coil unit (e.g., 1601, 1602, and 1603)of the variable refrigerant flow subsystem (e.g., 1600), and the supplyairstream provides a dedicated outdoor air supply (DOAS, for example,1100) that serves the variable refrigerant flow subsystem (e.g., 1600).A particular example is a system (e.g., for controlling temperature andhumidity within a space in a building) that includes a variablerefrigerant flow subsystem (e.g., 1600) and a dedicated outdoor airsupply subsystem (e.g., 300, 1100, 1400, or 1500) that includes, arecovery wheel, a (e.g., desiccant-based) dehumidification wheel, aprimary cooling coil, and at least one condenser coil. System 1100,shown in FIG. 11, is an example of such a dedicated outdoor air supplysubsystem. Other examples are shown and described herein, including inFIGS. 14 and 15. In a number of embodiments, the variable refrigerantflow subsystem (e.g., 1600) includes multiple fan coil units (e.g.,1601, 1602, and 1603) serving multiple zones (e.g., zones 1, 2, and 3shown in FIG. 16) within the space. Further, in various embodiments, thededicated outdoor air supply subsystem (e.g., 300, 1100, 1400, or 1500)serves the multiple zones.

In some embodiments, a VRF system uses one or more coils in the DOAS,for example, as a condenser coil when operating (e.g., primarily) in acooling mode or as an evaporator coil when operating (e.g., primarily)in a heating mode. For instance, in some embodiments, a VRF system(e.g., 1600) uses the primary condenser coil (e.g., 1104 shown in FIG.14) or the secondary condenser coil (e.g., 140) as a condenser coil whenoperating (e.g., primarily) in a cooling mode or as an evaporator coilwhen operating (e.g., primarily) in a heating mode. In particularembodiments, the VRF system also has a separate (e.g., outdoor) air coilor heat exchanger (e.g., similar to one or more of the options describedbelow for heat exchanger 173) in addition to at least one coil in theDOAS. In other embodiments, the VRF system does not have a separate(e.g., outdoor) heat exchanger (e.g., similar to one or more of theoptions described below for heat exchanger 173) and only has at leastone coil in the DOAS [i.e., in addition to zone heat exchangers or zoneindoor air coils, for instance, in zone fan coil units (e.g., 1601,1602, and 1603)]. In still other embodiments, the VRF system has an(e.g., outdoor) heat exchanger (e.g., similar to one or more of theoptions described below for heat exchanger 173) but does not have a coilin the DOAS, as another example.

In some embodiments, the dedicated outdoor air supply (e.g., 1400 or1500) further includes an evaporative cooler (e.g., 1480, 1580, orboth), for example, that precools air, for instance, entering theprimary circuit condenser coil (e.g., 1104, 1504, or both). Inparticular embodiments, for example, the evaporative cooler (e.g., 1480)is located between the recovery wheel (e.g., 110) and the primarycircuit condenser coil (e.g., 1104), the exhaust airstream (e.g., 1115)passes through the evaporative cooler (e.g., 1480), or both. Further, insome embodiments, supplemental outdoor air (e.g., 1425) is added to theexhaust airstream of the dedicated outdoor air supply (e.g., subsystem).In various embodiments, the supplemental outdoor air (e.g., 1425) passesthrough the evaporative cooler (e.g., 1480 in FIG. 14 or 1580 in FIG.15), the supplemental outdoor air (e.g., 1425) passes through theprimary circuit condenser coil (e.g., 1104 shown in FIG. 14 or 1504 inFIG. 15) in some embodiments, after the supplemental outdoor air (e.g.,1425) passes through the evaporative cooler (e.g., 1480 in FIG. 14 or1580 in FIG. 15), or both. Still further, in a number of embodiments,supplemental outdoor air (e.g., 1425) is added to the exhaust airstream(e.g., 1115), the supplemental outdoor air (e.g., 1425) passes throughthe primary circuit condenser coil (e.g., 1104 in FIG. 14 or 1504 inFIG. 15), the supplemental outdoor air (e.g., 1425) is added to theexhaust airstream (e.g., 1115) between the recovery wheel (e.g., 110)and the primary circuit condenser coil (e.g., 1104), or a combinationthereof.

In various embodiments, the space includes multiple zones, and thesystem or method includes cooling each of the multiple zones with atleast one zone direct-expansion refrigeration circuit (e.g., 171 shownin FIG. 17). This can be done, for example, by operating a zonecompressor (e.g., 172), cooling a zone indoor air coil (e.g., 174), andrejecting heat from the zone (e.g., 177) through a zone (e.g., outdoor)heat exchanger (e.g., 173), for example. In various embodiments, the actof cooling each of the multiple zones (e.g., 177) with at least one zonedirect-expansion refrigeration circuit (e.g., 171) includes rejectingheat from the zone (e.g., 177) specifically to a geothermal heatexchanger (e.g., 173, for instance, the zone outdoor heat exchanger).Further, in various embodiments, for instance, each at least one zonedirect-expansion refrigeration circuit (e.g., 171) is a heat pump andthe method further includes heating each of the multiple zones (e.g.,177) with the at least one zone direct-expansion refrigeration circuit(e.g., 171), for example, by operating the zone compressor (e.g., 172),heating the zone indoor air coil (e.g., 174), and obtaining heat for thezone (e.g., in act 1260) through the zone outdoor heat exchanger (e.g.,173, for instance, a geothermal heat exchanger), for example.

In various embodiments, the system includes a geothermaldirect-expansion refrigeration circuit, for example, that uses ageothermal heat sink (e.g., 173) as a geothermal condenser in a coolingmode. Still further, in some embodiments, the space includes multiplezones. Further still, in certain embodiments, each of the multiple zonesincludes at least one zone direct-expansion refrigeration circuit, forexample, that includes a zone compressor, a zone indoor air coil, and azone outdoor heat exchanger. FIG. 17 illustrates direct-expansionrefrigeration circuit 171, for example, which includes compressor 172,outdoor heat exchanger or condenser 173 (i.e., a condenser whenoperating in a cooling mode), and indoor air coil 174. In the exampleshown, indoor air coil 174 is in air handling unit 175, that includesfan 176, and conditions zone 177. Zone 177 may be one zone of multiplezones that make up the space, for instance. Embodiments that condition azone (e.g., 177) may include a zone compressor (e.g., 172), a zoneindoor air coil (e.g., 174), and a zone outdoor heat exchanger (e.g.,173), which may be in two or more enclosures (e.g., a split system), ormay all be in one enclosure (e.g., a packaged unit), as examples. Incertain embodiments, outdoor heat exchanger or condenser 173 (i.e., acondenser when operating in a cooling mode) is a geothermal heat sink(e.g., in a geothermal well or geothermal well field) and circuit 171 isa geothermal direct-expansion refrigeration circuit. Thus, among otherthings, circuit 171 is an example of a geothermal direct-expansionrefrigeration circuit that uses a geothermal heat sink (e.g., 173) as ageothermal condenser in a cooling mode. In other embodiments, outdoorheat exchanger or condenser 173 is a different type of heat exchanger,for example, one that rejects heat to air (e.g., outdoor air, exhaustair, or both, for instance, as described herein). Further, in certainembodiments, for example, outdoor heat exchanger or condenser 173 is orincludes a cooling tower, for instance that rejects heat to air (e.g.,outdoor air). Further, in particular embodiments, the primary coolingsystem is a direct expansion circuit (e.g., 171 or similar to 171) andthe primary cooling coil (e.g., 150, 350, 1050, or 1150) can besubstituted for coil 174 in FIG. 17.

Various embodiments (e.g., of a system for controlling temperature andhumidity within a space in a building) include a geothermal heat sink(e.g., 173 shown in FIG. 17). In some embodiments, for example, heatfrom the primary cooling coil (e.g.,150, 350, or 1150) is rejected tothe geothermal heat sink (e.g., 173) or the condensing coil (e.g., 173)for the primary direct expansion circuit (e.g., 171) is the geothermalheat sink. Still further, some embodiments (e.g., of a system forcontrolling temperature and humidity within a space in a building)include a direct-expansion refrigeration circuit (e.g., 171), forinstance, that uses the geothermal heat sink (e.g., 173) as a geothermalcondenser in a cooling mode. Even further, in various embodiments, thedirect-expansion refrigeration circuit (e.g., 171) uses the geothermalheat sink (e.g., 173) as an evaporator in a heating mode. Further still,in some embodiments, the direct-expansion refrigeration circuit (e.g.,171) is a primary direct-expansion refrigeration circuit, or the system(e.g., 100, 300, or 1100) includes a primary direct-expansionrefrigeration circuit (e.g., 171) that uses the primary cooling coil(e.g., 150, 350, or 1150) as a primary evaporator (e.g., in place ofzone indoor air coil 174 shown in FIG. 17). In some embodiments, forexample, the primary direct-expansion refrigeration circuit is a heatpump that both cools and heats the primary cooling coil (e.g., 150, 350,or 1150) depending on whether cooling or heating of the space isdemanded (e.g., by at least one thermostat located within the space). Ina number of embodiments, when the system (e.g., 100, 300, or 1100) isoperating in a heating mode, the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) is turned off, and when thesystem is operating in a cooling mode, the secondary direct-expansionrefrigeration circuit (e.g., 125 or 325) is turned on.

FIG. 18 illustrates chilled water system 180 that includes chiller 182,cooling tower 183, and cooling coil 184. Cooling coil 184, in a numberof embodiments, is a heat exchanger that cools air using chilled waterdelivered from chiller 182 through conduit 181. In some embodiments, forexample, a system (e.g., 100 or 300) includes a primary chiller (e.g.,182 shown in FIG. 18), for example, that chills cooling water (e.g.,delivered from chiller 182 in cooling water conduit 181) that passesthrough the primary cooling coil (e.g.,150, 184, or 350). In someembodiments, the (e.g., primary) chiller (e.g., 182) includes multiplechillers. Moreover, in various embodiments, the (e.g., primary) chiller(e.g., 182) is separate from the secondary direct-expansionrefrigeration circuit system (e.g., 125 or 325) or compressor (e.g., 120or 320), or from both.

In various embodiments, the system (e.g., for controlling temperatureand humidity within a space in a building) further includes multiplechilled beams, for example, located within the space, for instance,within the zones. Heat exchanger 184 in chiller system 180 shown in FIG.18 can be or include one or more chilled beams, for example. Further, ina number of embodiments, the system includes a main chiller (e.g., 182)that chills cooling water (e.g., delivered in conduit 181) that passesthrough the (e.g., multiple) chilled beams (e.g., 184). Still further,in some embodiments, the cooling water (e.g., in conduit 181) from themain chiller (e.g., 182) also passes through the primary cooling coil(e.g., 150 or 350), for example, in parallel, or in series (e.g., firstthrough the primary cooling coil, for example, 150 or 350). Heatexchanger 184 in FIG. 18, in some embodiments, is or includes theprimary cooling coil. In some embodiments, the primary chiller and themain chiller, as described herein, are the same chiller (or chillers,for example, 182) while in other embodiments, the primary chiller andthe main chiller are separate chillers (or sets of chillers). Evenfurther, in various embodiments, the multiple chilled beams (e.g., 184,for instance, located within the space or zones) are active chilledbeams. Further still, in a number of embodiments, the supply airstream(e.g., 335 or 1135) that passes to the space is delivered to themultiple chilled beams (e.g., 184) located within the space. Evenfurther still, in some embodiments, the supply airstream (e.g., 335 or1135, for instance, that passes to the space) induces room air in thespace over or across cooling coils within the multiple chilled beams(e.g., 184), for example, enhancing cooling capacity delivered by themultiple chilled beams. As used herein, in this context, “over” includesalong and in contact with. In some embodiments, the room air movesthrough passageways or between fins of the chilled beams, as examples.

In some embodiments, the system (e.g., system controller) or individualzones (e.g., pump modules or zone controllers), for example, usetemperature and relative humidity in each zone (e.g., of the multiplezone system) to calculate the absolute humidity level (e.g., in eachzone), then use the maximum humidity level measured in all of themultiple zones to increase or decrease the humidity level delivered bythe system (e.g., DOAS, for instance, serving zones containing chilledbeams) to process the latent load within the multiple zones, forexample, and avoid condensation on the chilled beams. Further, inparticular embodiments, a maximum absolute humidity setpoint isassigned, for example, to the multiple zones, and in certainembodiments, when any zone exceeds this humidity level, the supply airhumidity setpoint from the DOAS is (e.g., incrementally) decreased, forexample, at a predetermined rate, for instance, until all zones are(e.g., at least) controlled to the maximum absolute humidity setpoint.Still further, in some embodiments, a maximum absolute humidity setpointis assigned to the multiple zones, and when all zones are below thishumidity level setpoint, the supply air humidity setpoint from the DOASis (e.g., incrementally) increased, for instance, at a predeterminedrate, for example, until all zones are (e.g., at least) controlled at orbelow the maximum absolute humidity setpoint. Even further, inparticular embodiments, a supply air temperature setpoint is assignedand the setpoint is increased or decreased (e.g., incrementally), forexample, based upon the heating and cooling status of the pump modulesserving the multiple zones. Further still, in certain embodiments, allzones are monitored, for example, to determine if the zones arerequesting heating, requesting cooling, or are satisfied. Even furtherstill, in particular embodiments, the number of heating or coolingrequests are used to determine a global heating or cooling priority, forexample, of the chilled beam pump modules serving the multiple spaces orzones, for instance, which decides whether spaces calling for cooling orheating get satisfied first (e.g., chilled water or hot water isdelivered, for example, first). Moreover, in some embodiments, theheating and cooling priority mode control computations are made by theonboard DDC control system of the dedicated outdoor air supply subsystem(DOAS). Furthermore in some embodiments, the heating and coolingpriority mode control computations are made by the building automatedcontrol system (BAS), for example, communicating with the multiple zonepump modules, the DOAS, or both.

Further, various embodiments of the subject matter described hereininclude various combinations of the acts, structure, components, andfeatures described herein, shown in the drawings, described in documentsthat are submitted herewith or incorporated by reference herein, or thatare known in the art. Moreover, certain procedures can include acts suchas manufacturing, obtaining, or providing components that performfunctions described herein or in the documents that are incorporated byreference. The subject matter described herein also includes variousmeans for accomplishing the various functions or acts described herein,in the documents that are submitted herewith or incorporated byreference, or that are apparent from the structure and acts described.Each function described herein is also contemplated as a means foraccomplishing that function, or where appropriate, as a step foraccomplishing that function. Further, as used herein, the word “or”,except where indicated otherwise, does not imply that the alternativeslisted are mutually exclusive. Even further, where alternatives arelisted herein, it should be understood that in some embodiments, feweralternatives may be available, or in particular embodiments, just onealternative may be available, as examples.

What is claimed is:
 1. A system for controlling temperature and humiditywithin a space in a building, the system comprising: a recovery wheel; adesiccant-based dehumidification wheel; a primary cooling coil; asecondary direct-expansion refrigeration circuit comprising a secondarycircuit compressor, a secondary circuit evaporator coil, and a secondarycircuit condenser coil; and multiple chilled beams located within thespace; wherein: the space comprises multiple zones and each zone of themultiple zones comprises at least one of the multiple chilled beams thatare located within the space; the system forms a supply airstream thatpasses outdoor air first through the recovery wheel, then through theprimary cooling coil, then through the desiccant-based dehumidificationwheel, and then to the space; and the system forms an exhaust airstreamthat passes return air from the space through the desiccant-baseddehumidification wheel and then through the recovery wheel.
 2. Thesystem of claim 1 wherein the supply airstream passes the outdoor airfirst through the recovery wheel, then through the primary cooling coil,then through the secondary circuit evaporator coil, then through thedesiccant-based dehumidification wheel, and then to the space.
 3. Thesystem of claim 1 wherein the exhaust airstream passes the return airfrom the space first through the secondary circuit condenser coil, thenthrough the desiccant-based dehumidification wheel, and then through therecovery wheel.
 4. The system of claim 1 further comprising a mainchiller that chills cooling water that passes through the multiplechilled beams located within the space; wherein the cooling water fromthe main chiller also passes through the primary cooling coil.
 5. Thesystem of claim 1 wherein: the multiple chilled beams located within thespace are active chilled beams; the supply airstream that passes to thespace is delivered to the multiple chilled beams located within thespace; and the supply airstream that passes to the space induces roomair in the space over coils contained within the multiple chilled beamsenhancing cooling capacity provided by the multiple chilled beams. 6.The system of claim 1 wherein: the supply airstream that passes to thespace fully handles latent load of the space; and the chilled beamshandle only sensible load of the space.
 7. The system of claim 1 furthercomprising multiple pump modules wherein each pump module of themultiple pump modules comprises a zone pump that delivers cooling waterto at least one of the multiple chilled beams located in at least onezone of the multiple zones.
 8. The system of claim 7 wherein each pumpmodule of the multiple pump modules comprises: a temperature sensor thatmeasures temperature of the cooling water delivered to the at least oneof the multiple chilled beams located in the at least one zone of themultiple zones; a cooling water control valve that controls passage ofcooling water from a cooling water supply header into the pump module ofthe multiple pump modules to be delivered by the zone pump to the atleast one of the multiple chilled beams located in the at least one zoneof the multiple zones; and a digital controller that controls thecooling water control valve to control temperature of cooling waterdelivered by the zone pump to the at least one of the multiple chilledbeams located in the at least one zone of the multiple zones.
 9. Thesystem of claim 8 wherein the digital controller controls the coolingwater control valve to limit flow of cooling water from the coolingwater supply header based on a measurement of room air humidity or dewpoint temperature within the zone of the multiple zones at a humidistatlocated with the zone of the multiple zones to avoid formation ofcondensation on the at least one of the multiple chilled beams locatedin the at least one zone of the multiple zones by avoiding having partof the at least one of the multiple chilled beams drop below the dewpoint temperature within the zone of the multiple zones.
 10. The systemof claim 1 wherein: the recovery wheel is a total energy recovery wheelcomprising a desiccant coating; the recovery wheel transfers sensibleheat between the outdoor air of the supply airstream and the exhaustairstream; the recovery wheel transfers moisture between the outdoor airof the supply airstream and the exhaust airstream; the desiccant-baseddehumidification wheel is a passive dehumidification wheel; and thesystem further comprises: a supply fan located in the supply airstreamthat moves the outdoor air first through the recovery wheel, thenthrough the primary cooling coil, then through the desiccant-baseddehumidification wheel, and then to the space; an exhaust fan located inthe exhaust airstream that moves the return air from the space throughthe desiccant-based dehumidification wheel and then through the recoverywheel; and a partition between the supply airstream and the exhaustairstream wherein: the recovery wheel is located in a first opening inthe partition; the desiccant-based dehumidification wheel is located ina second opening in the partition; and at least adjacent to thepartition, the supply airstream and the exhaust airstream travel insubstantially opposite directions; and an enclosure that contains therecovery wheel, the desiccant-based dehumidification wheel, the primarycooling coil, the secondary circuit evaporator coil, the secondarycircuit condenser coil, at least part of the supply airstream, at leastpart of the exhaust airstream, and the partition.
 11. The system ofclaim 1 further comprising a system controller configured to: operatethe secondary circuit compressor whenever the system is operating in acooling mode; operate the secondary circuit compressor whenever thesystem is operating in a dehumidification mode; modulate cooling at theprimary cooling coil to control temperature of the space when operatingin the cooling mode; modulate cooling at the primary cooling coil tocontrol absolute humidity level or dew point of the space when operatingin the dehumidification mode; modulate cooling at the primary coolingcoil to control temperature of the supply airstream delivered to thespace when operating in the cooling mode; and modulate cooling at theprimary cooling coil to control absolute humidity level or dew point ofthe supply airstream delivered to the space when operating in thedehumidification mode.
 12. The system of claim 1 further comprising asystem controller configured to modulate the secondary circuitcompressor to adjust reheat capacity at the secondary condenser coilwhen operating in a cooling mode.
 13. The system of claim 1 furthercomprising a system controller configured to modulate rotational speedof the dehumidification wheel based on a measured temperature of thesupply airstream delivered to the space to control temperature of thesupply airstream delivered to the space.
 14. The system of claim 1further comprising a system controller configured to operate the systemin an economizer mode in which cooling at the primary cooling coil isturned off and the secondary circuit compressor is operated todehumidify the supply airstream with the secondary circuit evaporatorcoil and the desiccant-based dehumidification wheel.
 15. The system ofclaim 1 further comprising a system controller configured to operate thesystem in a part-load or recirculation mode in which cooling at theprimary cooling coil is modulated down or off and cooling at thesecondary cooling coil is modulated to dehumidify the supply airstreamusing the desiccant-based dehumidification wheel.
 16. The system ofclaim 1 further comprising a system controller configured to: lowerspeed or capacity of the secondary direct expansion circuit compressoror lower rotational speed of the dehumidification wheel when dew pointor humidity level in the space drops below a setpoint dew point orhumidity level threshold; and increase speed or capacity of thesecondary direct expansion circuit compressor or increase rotationalspeed of the dehumidification wheel when dew point or humidity level inthe space exceeds the setpoint dew point or humidity level threshold.17. The system of claim 1 further comprising a system controllerconfigured to: lower speed or capacity of the secondary direct expansioncircuit compressor when dew point or humidity level in the space dropsbelow a setpoint dew point or humidity level threshold when supply airtemperature or space temperature is below a setpoint temperaturethreshold; increase the speed or capacity of the secondary directexpansion circuit compressor when the dew point or humidity level in thespace exceeds the setpoint dew point or humidity level threshold whenthe supply air temperature or the space temperature is above thesetpoint temperature threshold; lower rotational speed of thedehumidification wheel and maintain speed or capacity of the secondarydirect expansion circuit compressor when dew point or humidity level inthe space drops below the setpoint dew point or humidity level thresholdand supply air temperature or space temperature is above the temperaturesetpoint threshold; and increase the rotational speed of thedehumidification wheel and maintain the speed or capacity of thesecondary direct expansion circuit compressor when the dew point orhumidity level in the space or supply air exceeds the setpoint dew pointor humidity level threshold and the supply air temperature or spacetemperature is below the temperature setpoint threshold.
 18. The systemof claim 1 wherein the system controls temperature and humidity withinthe space in the building, including simultaneously: operating thesecondary circuit compressor of the secondary direct-expansionrefrigeration circuit; passing the outdoor air first through therecovery wheel, then through the primary cooling coil, then through thesecondary circuit evaporator coil, then through the desiccant-baseddehumidification wheel, and then to the space; and passing the returnair from the space first through the secondary circuit condenser coil,then through the desiccant-based dehumidification wheel, and thenthrough the recovery wheel.
 19. The system of claim 1 wherein the systemsimultaneously: transfers a first quantity of heat from the outdoor airentering the supply airstream to the exhaust airstream; cools the supplyairstream downstream of where the system transfers the first quantity ofheat, including condensing a second quantity of moisture from the supplyairstream; transfers a third quantity of heat from the supply airstreamto the return air entering the exhaust airstream, wherein: the thirdquantity of heat is transferred from the supply airstream downstream ofwhere the system condenses the second quantity of moisture from thesupply airstream; transferring of the third quantity of heat from thesupply airstream includes condensing a fourth quantity of moisture fromthe supply airstream; transferring of the third quantity of heat fromthe supply airstream to the return air entering the exhaust airstream isperformed using the secondary direct-expansion refrigeration circuit;transfers a fifth quantity of moisture from the supply airstream to theexhaust airstream, wherein the fifth quantity of moisture is transferredfrom the supply airstream to the exhaust airstream in the supplyairstream downstream of where the third quantity of heat is transferredfrom the supply airstream to the return air entering the exhaustairstream, and wherein the fifth quantity of moisture is transferredfrom the supply airstream to the exhaust airstream in the exhaustairstream downstream of where the third quantity of heat is transferredfrom the supply airstream to return air entering the exhaust airstream;in conjunction with transferring the fifth quantity of moisture from thesupply airstream to the exhaust airstream, the system transfers a sixthquantity of sensible heat from the exhaust airstream to the supplyairstream, wherein transferring the sixth quantity of sensible heat fromthe exhaust airstream to the supply airstream takes place in the supplyairstream downstream of where the third quantity of heat is transferredfrom the supply airstream to the return air entering the exhaustairstream, and wherein the sixth quantity of sensible heat istransferred from the exhaust airstream to the supply airstream in theexhaust airstream downstream of where the third quantity of heat istransferred from the supply airstream to the return air entering theexhaust airstream; and delivers the supply airstream to the spacedownstream of where the sixth quantity of sensible heat is transferredfrom the exhaust airstream to the supply airstream; wherein: deliveringof the supply airstream to the space takes place in the supply airstreamdownstream of where the fifth quantity of moisture is transferred fromthe supply airstream to the exhaust airstream; and the first quantity ofheat is transferred from the outdoor air entering the supply airstreamto the exhaust airstream in the exhaust airstream downstream of wherethe fifth quantity of moisture is transferred from the supply airstreamto the exhaust airstream.
 20. The system of claim 19 wherein: the firstquantity of heat comprises both sensible and latent heat; transferringthe first quantity of heat from the outdoor air entering the supplyairstream to the exhaust airstream further comprises transferring aseventh quantity of moisture from the outdoor air entering the supplyairstream to the exhaust airstream; the transferring of the seventhquantity of moisture from the outdoor air entering the supply airstreamto the exhaust airstream takes place in the exhaust airstream downstreamof where the fifth quantity of moisture is transferred from the supplyairstream to the exhaust airstream; and cooling of the supply airstreamdownstream of the transferring of the first quantity of heat comprisesremoving an eighth quantity of heat from the supply airstream andrejecting the eighth quantity of heat to the exhaust airstreamdownstream of where the first quantity of heat is transferred to theexhaust airstream.